[CI] Improvement and fixes (#161)

* protocols: Fix building without the "games" feature

* crate/lib: Add required features for examples

This prevents cargo from running the examples if the required features
aren't enabled.

* ci: Run if ANY Cargo.toml files are changed

* ci: Make sure to run unit tests

* ci: Separate checks for library and CLI

* ci: Add slightly better comments

* ci: Only run deeper tests for CLI or LIB when their files were changed

* ci: Improve act arguments for testing actions locally

* ci: Fix pre-commit not running tests

* ci: Only update shared cache after the initial build

* ci: Make sure that rustup downloads get cached

* tidy: Clean up file formatting

* ci: Fix issue with audit

.github/.act-event.json

@@ -0,0 +1,6 @@
+{
+    "act": true,
+    "repository": {
+        "default_branch": "main"
+    }
+}