Provide a way to exclude Glean from Fenix

[sysrqb]

Why/User Benefit/User Problem

Build a "flavor" of Fenix without Glean. This is helpful for non-Mozilla builds of Fenix where the resulting browser has strict data-sharing (no telemetry) and networking requirements.

What/Requirements

Add a built-time control mechanism for excluding Glean. This could be a new build config property or a new build type.

Acceptance Criteria (how do I know when I’m done?)

Fenix builds/runs/doesn't-crash (and all of the unit tests pass, except for Glean-specific tests)

┆Issue is synchronized with this Jira Task

[sysrqb]

I got this working by adding a buildSrc Config paramter as a flag for toggling when Glean should be included as an implementation dependency or compileOnly dependency.

sysrqb@fd42637

This patch includes more than simply including/excluding Glean (such as hiding the Data Collection setting).

I'm looking for a way of doing this such that we can extend it to megazoid components, as well. The proposed patch only requires minimal code changes, and only introduces a dependency on BuildConfig.

I'm having trouble excluding source files in build.gradle (in particular, unit test files for testing Glean), but that's likely a separate issue.

Any feedback about improvements/suggestions and what you would consider accepting (or what you won't accept upstream), are all helpful.

[androidacy-user]

Personally anything that allows for a purely FOSS build, such as the current F-Droid edition I think is a great idea.

[csadilek]

Moved to bugzilla: https://bugzilla.mozilla.org/show_bug.cgi?id=1809318

Change performed by the Move to Bugzilla add-on.