Fix a regression caused by jQuery removal (`renderPreviewPanelContent`)
And simplify the file editor, it doesn't need to be that complex. And
remove jQuery code.
1. correct the modal usage on "admin email list" page (then
`web_src/js/features/admin/emails.ts` is removed)
2. use `addDelegatedEventListener` instead of `jQuery().on`
3. more jQuery related changes and remove jQuery from
`web_src/js/features/common-button.ts`
4. improve `confirmModal` to make it support header, and remove
incorrect double-escaping
5. fix more typescript related types
6. fine tune devtest pages and add more tests
Many files do not directly depend on jQuery now.
To clarify the usage: use `fomanticQuery` to operate Fomantic
components.
Then developers could focus on removing the remaining jQuery usages by
searching `import $` globally.
21 files now:
```
./components/RepoBranchTagSelector.vue:3:import $ from 'jquery';
./features/admin/common.ts:1:import $ from 'jquery';
./features/admin/emails.ts:1:import $ from 'jquery';
./features/common-button.ts:1:import $ from 'jquery';
./features/comp/ComboMarkdownEditor.ts:3:import $ from 'jquery'; (I am working on it, there will be a new PR)
./features/comp/LabelEdit.ts:1:import $ from 'jquery';
./features/notification.ts:1:import $ from 'jquery';
./features/org-team.ts:1:import $ from 'jquery';
./features/repo-code.ts:1:import $ from 'jquery';
./features/repo-common.ts:1:import $ from 'jquery';
./features/repo-diff.ts:1:import $ from 'jquery';
./features/repo-editor.ts:1:import $ from 'jquery';
./features/repo-issue-content.ts:1:import $ from 'jquery';
./features/repo-issue-list.ts:1:import $ from 'jquery';
./features/repo-issue-sidebar.ts:1:import $ from 'jquery';
./features/repo-issue.ts:1:import $ from 'jquery';
./features/repo-legacy.ts:1:import $ from 'jquery';
./features/repo-new.ts:1:import $ from 'jquery';
./features/repo-projects.ts:1:import $ from 'jquery';
./features/repo-settings.ts:1:import $ from 'jquery';
./features/repo-template.ts:1:import $ from 'jquery';
```
None of the frontend js/ts files was touched besides these two commands
(edit: no longer true, I touched one file in
61105d0618
because of a deprecation that was not showing before the rename).
`tsc` currently reports 778 errors, so I have disabled it in CI as
planned.
Everything appears to work fine.
