Misc JS linting and naming tweaks (#10652)

- lowercase all js filenames except Vue components
- enable new lint rules, mostly focused on shorter code
- autofix new lint violations
- apply misc transformations indexOf -> includes and onevent-> addEventListener

Co-authored-by: Antoine GIRARD <sapk@users.noreply.github.com>

.eslintrc

@@ -5,7 +5,7 @@ extends:
   - eslint:recommended
 
 ignorePatterns:
- - /web_src/js/vendor
+  - /web_src/js/vendor
 
 parserOptions:
   ecmaVersion: 2020
@@ -26,19 +26,22 @@ globals:
 
 rules:
   arrow-body-style: [0]
+  arrow-parens: [2, always]
   camelcase: [0]
   comma-dangle: [2, only-multiline]
   consistent-return: [0]
   default-case: [0]
   func-names: [0]
-  import/extensions: [0]
+  import/extensions: [2, always, {ignorePackages: true}]
   import/prefer-default-export: [0]
   max-len: [0]
+  multiline-comment-style: [2, separate-lines]
   newline-per-chained-call: [0]
   no-alert: [0]
   no-cond-assign: [2, except-parens]
   no-console: [1, {allow: [info, warn, error]}]
   no-continue: [0]
+  no-eq-null: [2]
   no-mixed-operators: [0]
   no-multi-assign: [0]
   no-new: [0]
@@ -49,8 +52,12 @@ rules:
   no-unused-vars: [2, {args: all, argsIgnorePattern: ^_, varsIgnorePattern: ^_, ignoreRestSiblings: true}]
   no-use-before-define: [0]
   no-var: [2]
+  object-curly-spacing: [2, never]
   one-var-declaration-per-line: [0]
   one-var: [0]
+  operator-linebreak: [2, after]
   prefer-const: [2, {destructuring: all}]
   prefer-destructuring: [0]
+  quotes: [2, single, {avoidEscape: true, allowTemplateLiterals: true}]
   radix: [2, as-needed]
+  semi: [2, always, {omitLastInOneLineBlock: true}]