Create shortcuts in subdirectory

[j8r]

Description

Fixes #2264 by creating and giving the rights to create shortcuts into a specific applications directory.
We no longer need to run flatpak override com.usebottles.bottles --user --filesystem=xdg-data/applications, the permission is given by default.
There is no security application since Bottles only has the right to create and remove shortcuts in its specific ~/.local/share/applications/bottles directory.
~/.local/share/applications still need to exist.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.
Provide instructions so we can reproduce.

• build flatpak run org.flatpak.Builder --user --install --force-clean --ccache build-dir com.usebottles.bottles.yml
• run flatpak run --env=DEBUG_MODE=true com.usebottles.bottles
• create a bottle then a shortcut
• remove the shortcut and/or bottle

[j8r]

No idea why the linter fails, not related to the changes I made.

[orowith2os]

We should use the DynamicLauncher portal, not write to the paths directly. It's been discussed in the past. Permissions like this are best documented and added by the end user for the time being.

Wrt. the DynamicLauncher portal, PRs welcome.