linux: add app identity override for DBus / desktop integration

[glchr]

As a heavy Discord multi-account user, I wanted to make it possible to run several Equibop instances without them colliding in Dbus notifications.

Right now several points assume a hardcoded name equibop which causes issues with for example task manager badges (where every instance running gets its badge count set by any instance that tries to update the badge for itself).

PR adds support for extra CLI arg:

• --app-name <id>: overrides the app identity used for desktop / DBus-related integration

Default behavior is unchanged:

• if --app-name is not provided, everything still behaves as equibop

Example code I use for multi-accounts:

equibop --user-data-dir=/path/to/profile --app-name my-profile

Note: In KDE, for this to work correctly, the app-name needs to match the .desktop file's filename (eg. my-profile for my-profile.desktop entry).

[Creationsss]

i dont really see a point in

"equibop" ? "Equibop"

[glchr]

• Default desktop entry is Equibop, like it was pre-changes in this PR
• Default appname is equibop, as per above

The idea was to make sure Equibop doesn't change anything in how it announces itself unless --app-name parameter is passed. Using simply Name=${AppName} results in lowercase equibop when no parameter is passed.