[web-client] simple theme: refactor jinja_svg_catalog and cleanup icon names

This patch implements the template generation of the template:

  searx/templates/simple/icons.html

by the way the icon set (the icon names) has been normalized:

  film-outline   --> film
  magnet-outline --> magnet
  ..
  warning        --> alert

Some missing (categorie) icons had been added.

Some of the ionicons are not suitable for a dark theme, we fixed the svg
manually in src/svg/ionicons:

- https://github.com/searxng/searxng/pull/4284#issuecomment-2680550342

Signed-off-by: Markus Heiser <markus.heiser@darmarit.de>

client/simple/tools/jinja_svg_catalog.html.edge

@@ -0,0 +1,26 @@
+{{--
+This is a EDGE https://edgejs.dev/ template to generate a HTML Jinja template
+for the backend.  Example output of this EDGE template:
+- https://github.com/searxng/searxng/blob/master/searx/templates/simple/icons.html
+--}}
+{#
+Catalog of SVG symbols that can be inserted into the HTML output of a Jinja
+template. This file from:
+
+  client/simple/tools/icon_catalog.edge.html
+#}
+
+{%-
+set catalog = {
+@each((svg, name) in svg_catalog)
+    "{{{name}}}" : """{{{svg}}}""",
+@end
+}
+-%}
+
+@each(macro in macros)
+
+{% macro {{ macro.name }}(action, alt) -%}
+  {{ open_curly_brace }} catalog[action] | replace("{{__jinja_class_placeholder__}}", "{{ macro.class }}") | safe {{ close_curly_brace }}
+{%- endmacro %}
+@end

client/simple/tools/jinja_svg_catalog.js

@@ -0,0 +1,130 @@
+import fs from "fs";
+import { resolve, dirname } from "path";
+import { Edge } from 'edge.js';
+import { optimize as svgo } from "svgo";
+import { fileURLToPath } from 'url';
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const __jinja_class_placeholder__ = "__jinja_class_placeholder__";
+
+// -- types
+
+/**
+ * @typedef {object} IconSet - A set of icons
+ * @property {object[]} set - Array of SVG icons, where property name is the
+ * name of the icon and value is the src of the SVG (relative to base).
+ * @property {string} base - Folder in which the SVG src files are located.
+ * @property {import("svgo").Config} svgo_opts - svgo options for this set.
+ */
+
+/**
+ * @typedef {object} IconSVG - Mapping of icon name to SVG source file.
+ * @property {string} name - Name of the icon isource file.
+ * @property {string} src - Name of the destination file.
+ * @property {import("svgo").Config} svgo_opts - Options passed to svgo.
+ */
+
+/**
+ * @typedef {object} JinjaMacro - Arguments to create a jinja macro
+ * @property {string} name - Name of the jinja macro.
+ * @property {string} class - SVG's class name (value of XML class attribute)
+ */
+
+
+// -- functions
+
+/**
+ * Generate a jinja template with a catalog of SVG icons that can be
+ * used in in other HTML jinja templates.
+ *
+ * @param {string} dest - filename of the generate jinja template.
+ * @param {JinjaMacro} macros - Jinja macros to create.
+ * @param {IconSVG[]} items - Array of SVG items.
+ */
+
+function jinja_svg_catalog(dest, macros, items) {
+
+  const svg_catalog = {};
+  const edge_template = resolve(__dirname, "jinja_svg_catalog.html.edge");
+
+  items.forEach(
+    (item) => {
+
+      /** @type {import("svgo").Config} */
+      const svgo_opts = JSON.parse(JSON.stringify(item.svgo_opts));
+      svgo_opts.plugins.push({
+        name: "addAttributesToSVGElement",
+        params: {
+          attributes: [{ "class": __jinja_class_placeholder__, }]
+        }}
+      );
+
+      try {
+        const raw = fs.readFileSync(item.src, "utf8");
+        const opt = svgo(raw, svgo_opts);
+        svg_catalog[item.name] = opt.data;
+      } catch (err) {
+        console.error(`ERROR: jinja_svg_catalog processing ${item.name} src: ${item.src} -- ${err}`);
+        throw(err);
+      }
+    }
+  );
+
+  fs.mkdir(dirname(dest), { recursive: true }, (err) => {
+    if (err) throw err;
+  });
+
+  const ctx = {
+    svg_catalog: svg_catalog,
+    macros: macros,
+    edge_template: edge_template,
+    __jinja_class_placeholder__: __jinja_class_placeholder__,
+    // see https://github.com/edge-js/edge/issues/162
+    open_curly_brace : "{{",
+    close_curly_brace : "}}"
+  };
+
+  const jinjatmpl = Edge.create().renderRawSync(
+	  fs.readFileSync(edge_template, "utf-8"),
+	  ctx
+  );
+
+  fs.writeFileSync(dest, jinjatmpl);
+  console.log(`[jinja_svg_catalog] created: ${dest}`);
+}
+
+
+/**
+ * Calls jinja_svg_catalog for a collection of icon sets where each set has its
+ * own parameters.
+ *
+ * @param {string} dest - filename of the generate jinja template.
+ * @param {JinjaMacro} macros - Jinja macros to create.
+ * @param {IconSet[]} sets - Array of SVG sets.
+ */
+function jinja_svg_sets(dest, macros, sets) {
+  /** @type IconSVG[] */
+  const items = [];
+  const all = [];
+  for (const obj of sets) {
+
+    for (const [name, file] of Object.entries(obj.set)) {
+      if (all.includes(name)) {
+        throw new Error(`ERROR: ${name} has already been defined`);
+      }
+      items.push({
+        name: name,
+        src: resolve(obj.base, file),
+        svgo_opts: obj.svgo_opts,
+      });
+    }
+    jinja_svg_catalog(dest, macros, items);
+  }
+}
+
+// -- exports
+
+export {
+  jinja_svg_sets,
+  jinja_svg_catalog,
+};