Make installreferrer dependency optional for F-Droid

[jakubgs]

Description

During research done in #8512 and #11010 we found out that the dependency on installreferrer that we are adding in #10620 is incompatible with the FOSS-only requirement of the F-Droid catalog due to the license used.

There is a relatively recent issue for this: https://gitlab.com/fdroid/fdroidclient/-/issues/1932
But there is no conclusive decision.

Requirements

In order to make publishing to F-Droid possible we will need to be able to build a version of the release that does not include the dependency on installreferrer library. This should be achieved through settings in .env.* files or via a Gradle build flavor.