Add option to destroy MUC in the dropdown context menu.
Also add a confirmation dialog.

It can now happen because we also auto-complete for nicks based on
messages in the chat

bsaed on `muc_disable_slash_commands`

This causes messages to be created but then not populated, causing empty
messages appearing in the chat after page relaod.

Fixes #1886

Bumps [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) from 0.7.0 to 0.9.0.
- [Release notes](https://github.com/webpack-contrib/mini-css-extract-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/mini-css-extract-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/mini-css-extract-plugin/compare/v0.7.0...v0.9.0)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

before processing MUC messages received prematurely due to SMACKS
resumption.

Bumps [bootstrap](https://github.com/twbs/bootstrap) from 4.3.1 to 4.4.1.
- [Release notes](https://github.com/twbs/bootstrap/releases)
- [Commits](https://github.com/twbs/bootstrap/compare/v4.3.1...v4.4.1)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Also, don't set retracted MUC messages as ephemeral, we want to keep on
showing them to provide context in a MUC.

This reverts commit 776bbe74.

Goal is to fix a timing bug that results in `show` being triggered
before the `ChatBoxView` has been initialized, which means that 1:1
chats aren't opened when you reload the page.

Bumps [jsdoc](https://github.com/jsdoc/jsdoc) from 3.6.2 to 3.6.3.
- [Release notes](https://github.com/jsdoc/jsdoc/releases)
- [Changelog](https://github.com/jsdoc/jsdoc/blob/master/CHANGES.md)
- [Commits](https://github.com/jsdoc/jsdoc/compare/3.6.2...3.6.3)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [dayjs](https://github.com/iamkun/dayjs) from 1.8.15 to 1.8.20.
- [Release notes](https://github.com/iamkun/dayjs/releases)
- [Changelog](https://github.com/iamkun/dayjs/blob/dev/CHANGELOG.md)
- [Commits](https://github.com/iamkun/dayjs/compare/v1.8.15...v1.8.20)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 9.6.1 to 9.7.4.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/master/CHANGELOG.md)
- [Commits](https://github.com/postcss/autoprefixer/compare/9.6.1...9.7.4)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

- Get rid of the ChatBoxHeading class
- Add support for showing standalone buttons in overlay viewmode

This reverts commit 34436b7f.

I'm experiencing issues with map files while using the debugger in
the browser console.

Also move `custom_emojis` dir out of `dist` and copy it over as well.

Don't rewrite the urls for assets loaded via `url()` in CSS.

Instead, they should be relative to the CSS file.