Fix phpunit warnings and apply stricter CI checks

Since a few weeks I'm constantly seeing four warnings whenever
I attempt to run phpunit locally. As they didn't make out CI jobs
fail, nobody seemed to care. As that's a risky situation, I've
fixed all the reported warnings and - to ensure this doesn't happen
again - I've enabled failure on warnings.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Use Files icon for 'Add from Files' button

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Remove unused code

Fix translation string extractor for special characters

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Reduce date size and don't bold on unread

Signed-off-by: Jan-Christoph Borchardt <hey@jancborchardt.net>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Add OCP files as composer dependency

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Fix resumed draft to/cc/bcc values

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

AutoConfig: remove unused dependencies and extract method

Enhance loading view wording

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

This allows better CI analyses where Nextcloud's files are not
available because only the app repository is cloned.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Always treat the search mailbox as top level folder

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

Add more CSRF checks

Always log IMAP and SMTP if debug mode is enabled

* We don't use '…' anywhere for loading views
* Folder loaing message can cause problems with translations,
  e.g. for some languages the text is gramatically wrong.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>