LE Audio Broadcast assistant

[ldab]

LE audio broadcast assistant as implemented by https://github.com/AstraeusLabs/web-broadcast-assistant

It does something like this:

The code here is probably functional but partially untested as I do not have the HW now, I will test in few weeks when I go back to work.

• So the PR for now is more a general code review and if you happen to have 2x nRF5340 EVKs or a Galaxy Buds2 Pro you could help testing.
• The source files were excluded from the formater intentionally so it can be kept close to the source for future drop in.

If you want to test, build with CONFIG_APPLICATIONS_USE_LEA_ASSISTANT=y

[ldab]

Additionally, if you have an open unit it would be awesome to check the current when scanning, etc.