feat: Add partial quoting

- If you select a portion of the comment, `Quote reply` will not only
quote that portion and not copy paste the whole text as it previously
did. This is achieved by using the `@github/quote-selection` package.
- There's preprocessing to ensure Forgejo-flavored markdown syntax is
preserved.
- e2e test added.
- Resolves #1342

tests/e2e/fixtures/comment.yml

@@ -0,0 +1,22 @@
+-
+  id: 1001
+  type: 0 # comment
+  poster_id: 2
+  issue_id: 1 # in repo_id 1
+  content: "## Lorem Ipsum\nI would like to say that **I am not appealed** that it took _so long_ for this `feature` to be [created](https://example.com) $e^{\\pi i} + 1 = 0$\n$$e^{\\pi i} + 1 = 0$$\n#1\n```js\nconsole.log('evil')\nalert('evil')\n```\n:+1: :100:"
+  created_unix: 946684811
+  updated_unix: 946684811
+  content_version: 1
+
+-
+  id: 1002
+  type: 21 # code comment
+  poster_id: 2
+  issue_id: 19
+  content: "## Lorem Ipsum\nI would like to say that **I am not appealed** that it took _so long_ for this `feature` to be [created](https://example.com) $e^{\\pi i} + 1 = 0$\n$$e^{\\pi i} + 1 = 0$$\n#1\n```js\nconsole.log('evil')\nalert('evil')\n```\n:+1: :100:"
+  review_id: 1001
+  line: 1
+  tree_path: "test1.txt"
+  created_unix: 946684812
+  invalidated: false
+  content_version: 1

tests/e2e/fixtures/review.yml

@@ -0,0 +1,8 @@
+-
+  id: 1001
+  type: 22
+  reviewer_id: 1
+  issue_id: 2
+  content: "Review Comment"
+  updated_unix: 946684810
+  created_unix: 946684810