- add possibility to allow execution of the button's routine besides triggering
`toolbarButtonClicked` API event
- keep backwards compatibility
- get rid of `ToolbarButton`

Found via `codespell -q 3 -S ./lang`

Co-authored-by: Saúl Ibarra Corretgé <saghul@jitsi.org>
Co-authored-by: zycwind <391321232@qq.com>

Avoid importing components, which are not yet implemented on mobile.

- Adds the ability to share video as a "PiP" when screenshare is in progress.
- Add a method for creating a local presenter track.
- Make sure isLocalVideoTrackMuted returns the correct mute state when only screenshare is present.
- Make sure we get the updated window size of the window being shared before painting it on the canvas.
- Make sure we check if the shared window has been resized

This refactors all handling of audio-only and last N to 2 features in preparation
for "low bandwidth mode".

The main motivation to do this is that lastN is a "global" setting so it helps
to have all processing for it in a single place.

When the video unmute button disabled audio-only, also unmute video. This fixes
a weird case in which the user need to "unmute twice" if they were muted beofre
they enabled audio-only mode. That's ok if the audio-only button was used, but
not if the video-unmute button was used, since the expectation is to have video,
of course.

If audio-only was engaged, use the video (un)mute button to disengage it. This
should simplify the flow for getting back to video.

* fix(toolbar): accessibilityLabel should be translatable.

This commit adds a helper property to get the accessibilityLabel of an item,
providing a translation if one is available. This mimics the behavior of
label and tooltip.

* fix(toolbar) 'hangup' button accessibilityLabel i18n

* fix(toolbar) 'mute' button accessibilityLabel i18n

* fix(toolbar) 'videomute' button accessibilityLabel i18n

* fix(toolbar) 'moreActions' button accessibilityLabel i18n

* fix(toolbar) 'shareRoom' button accessibilityLabel i18n

* fix(toolbar) 'audioRoute' button accessibilityLabel i18n

* fix(toolbar) 'toggleCamera' button accessibilityLabel i18n

* fix(toolbar) 'audioOnly' button accessibilityLabel i18n

* fix(toolbar) 'roomLock' button accessibilityLabel i18n

* fix(toolbar) 'pip' button accessibilityLabel i18n

* fix(toolbar) 'invite' button accessibilityLabel i18n

* fix(toolbar) 'raiseHand' button accessibilityLabel i18n

* fix(toolbar) 'chat' button accessibilityLabel i18n

* fix(toolbar) 'shareYourScreen' button accessibilityLabel i18n

* fix(toolbar) 'fullScreen' button accessibilityLabel i18n

* fix(toolbar) 'sharedvideo' button accessibilityLabel i18n

* fix(toolbar) 'document' button accessibilityLabel i18n

* fix(toolbar) 'speakerStats' button accessibilityLabel i18n

* fix(toolbar) 'feedback' button accessibilityLabel i18n

* fix(toolbar) 'shortcuts' button accessibilityLabel i18n

* fix(toolbar) 'recording' button accessibilityLabel i18n

* fix(toolbar) 'settings' button accessibilityLabel i18n

* fix(welcomepage) accessibilityLabels i18n

* fix(toolbar) 'info' button accessibilityLabel i18n

* fix(i18n): Add translation to various aria-label property values.

* fix(i18n): Differentiate between overflow menu and button.

I don't think it's realistic that we'd merge a PR that breaks the most
important shortcuts of the app (in my opinion): audio and video
mute/unmute.

Contributing all buttons in one place goes against the designs that we
set out at the beginning of the project's rewrite and that multiple of
us have been following since then.

Currently the following are implemented:

- AudioMuteButton
- HangupButton
- VideoMuteButton

In order to implement these new buttons a new abstract class was introduced,
which abstracts the ToolboxItem into a button with enough hooks so a stateful
and a stateless version of it can be created.

This patch only adds the stateful implementation of the aforementioned buttons.