build: update melos configuration and update targets

melos.yaml

@@ -36,6 +36,18 @@ scripts:
   clean:deep:
     run: git clean -x -d -f -q
     description: Clean things very deeply with `git clean`.
+
+  test:selective_unit_test:
+    run: melos exec --dir-exists="test" -- flutter test --no-pub --coverage
+    description: Run Flutter tests for a specific package in this project.
+    select-package:
+      flutter: true
+
+  test:
+    run: melos run test:selective_unit_test --no-select
+    description: Run all Flutter tests in this project.
+
+  gen_coverage: melos exec -- sh "\$MELOS_ROOT_PATH/combine_coverage.sh" && genhtml coverage/lcov.info -o coverage/html
   
   # Additional cleanup lifecycle script, executed when `melos clean` is run.
   postclean: >