Rename JSX files with proper `.jsx` extension (#23733)

.eslintrc.js

.github/workflows/lint-js.yml

.github/workflows/test-js.yml

...s/__tests__/__snapshots__/autosuggest_emoji-test.jsx.snap

...n/components/__tests__/__snapshots__/avatar-test.jsx.snap

...ents/__tests__/__snapshots__/avatar_overlay-test.jsx.snap

...n/components/__tests__/__snapshots__/button-test.jsx.snap

...onents/__tests__/__snapshots__/display_name-test.jsx.snap

.../mastodon/components/__tests__/autosuggest_emoji-test.jsx

app/javascript/mastodon/components/__tests__/avatar-test.jsx

...ipt/mastodon/components/__tests__/avatar_overlay-test.jsx

app/javascript/mastodon/components/__tests__/button-test.jsx

...cript/mastodon/components/__tests__/display_name-test.jsx

app/javascript/mastodon/components/account.jsx

app/javascript/mastodon/components/admin/Counter.jsx

app/javascript/mastodon/components/admin/Dimension.jsx

...script/mastodon/components/admin/ReportReasonSelector.jsx

app/javascript/mastodon/components/admin/Retention.jsx

app/javascript/mastodon/components/admin/Trends.jsx

app/javascript/mastodon/components/animated_number.jsx