base,deps,src: Replace qr submodule by prefix/system install

[tytan652]

Description

Requires to work on obs-studio repo:

• Add Libqrcodegencpp obs-deps#182
• Add Libqrcodegencpp on Linux and add its finder obs-studio#8943
• Drop Ubuntu 20.04, related CI will failed because of an API break from Libqrcodegen between 1.5.0 (20.04) and 1.7.0 (22.04) (header file name change) with obs-websocket PRs.

Motivation and Context

Reduce to zero the number of submodule in obs-websocket repo.

How Has This Been Tested?

Tested OS(s): Arch Linux

Test binaries available on a PR on my obs-studio fork: tytan652/obs-studio#13

Types of changes

• Other Enhancement (anything not applicable to what is listed)

Checklist:

• I have read the Contributing Guidelines.
• All commit messages are properly formatted and commits squashed where appropriate.
• My code is not on master or a release/* branch.
• The code has been tested.
• I have included updates to all appropriate documentation.

[RytoEX]

All prerequisites have been resolved.