[S58] O2.2: Update build system for Fenix migration.

• Integrate Fenix and necessary dependencies into our reproducible builds system.
• Add new toolchains for targeted Fenix release.
• Verify that bundles are still reproducible after toolchain updates.

Trac:
Parent Ticket: #33657 (moved)
Child Ticket(s): #28704 (moved), #33184 (moved), #31915 (moved), #29615 (moved), #31992 (moved), #31161 (moved), #34015 (moved)

added component::applications/tor browser owner::tbb-team parent::33657 priority::medium severity::normal sponsor::58-must status::new type::project labels

Trac:
Sponsor: Sponsor58 to Sponsor58-must

mentioned in issue #34015 (moved)

mentioned in issue #34324 (moved)

mentioned in issue #29615 (moved)

mentioned in issue #31161 (moved)

mentioned in issue #31915 (moved)

mentioned in issue #31992 (moved)

mentioned in issue #33184 (moved)

mentioned in issue #33657 (moved)

moved to tpo/applications/tor-browser#33659 (closed)