`.forEach` on a Collection no longer returns the models, so need to
update some tests.

Queue messages and handle them sequentially, each time waiting for promises to
resolve before handling the next message.

Updates #1899, which likely happens because an error message is received
before messages have been fetched.

To avoid one test which times out, causing subsequent tests to not be
run (and therefore also time out).

Otherwise we run into race conditions while testing

In order to give plugins time to properly clear data from the browser storage.

* fix issue https://github.com/conversejs/converse.js/issues/1896

* Added issue to CHANGES.md

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>