Recording screenshare audio fixes

Fix https://github.com/bigbluebutton/bbb-install/issues/413 in source

Disabling audio or video processing isn't really something that's part
of the working format (and at some point we might want to combine
audio+video processing together).

Move the setting of the '-an' and '-vn' options to where they're
required - as a detail of the EDL processing for video-only and
audio-only components of the output.

Honestly, the main reason for this change is that when testing alternate
working formats, I had accidentally dropped the '-vn' option from the
FFMPEG_WF_ARGS variable without noticing.

style(logo): centralize image

feat(web): set default logo

Change the custom logo style to centralize the logo image.

Add an option to set a default logo to be placed for all created meetings.

The default logo is inserted as a create meeting param for all meetings that
do not have a `logo` param defined. Two new properties were included at
bigbluebutton-web configuration:

- [Boolean] `useDefaultLogo`: enables/disables the use of the default logo
  disabled as default

- [String] `defaultLogoURL`: The default logo URL to be fetched by the client
  bigbluebutton logo as default

fix: z-index issue in firefox for captions

chore: bump to v2.3.12

fix(breakout rooms): waiting url state

Setting the waiting state false as default was leaving an open gap where
the users still did not have a valid breakout room's join url and it's
join button enabled.

Change the first waiting state to true and handle the join type as the
component finishes mounting. If it's a free to choose room scenario,
dispatch the whole Promise based solution and let it manage the waiting
state as the interval checks for the URL response.

chore: Pulled HTML5 locales on Aug 11, 2021

fix: Added a label to describe why breakout join may take long time

fix: Await valid url on breakout before allowing to join; with @Tainan404

chore: Pulled HTML5 locales - Aug 5, 2021

Add override locale support - guest wait page

Feat: added option to allow to use customStyleUrl from config

fix: override default locale api parameter

upgrade node-sass version

fix: handle case of freeJoin breakout with no users

fix: Re-subscribe user to guestUser collection on promotion/demotion

fix: Grant current-poll access to attendee presenter too