v7.0.0

• 4c4af09 version: bump to 7.0.0 (Alexandr Savca)
• 24107a4 ci: add test execution step to build workflow (Alexandr Savca)
• 7276209 build: make unit tests optional via 'tests' feature (Alexandr Savca)
• 1f12413 tests: add regression test for deferred signal handling (Alexandr Savca)
• 8cbfcae pkgutils: defer termination during package mutations (Alexandr Savca)
• 5ede669 tree: remove extra/flags-*.mk (Alexandr Savca)
• 41e0d3b ci: align build workflow with link_mode option (Alexandr Savca)
• b86333c build: remove b_lto=false from defaults (Alexandr Savca)
• afc3cc5 build: reformat options for consistency (Alexandr Savca)