ci: add example-test workflow for testing and building examples (#211)

This workflow sets up a new CI job to handle testing and building of example projects in the repository. It includes setting up Node.js, Rust, Python, and necessary caching to ensure proper environment preparation. Example directories are iterated to run tests and builds for each valid Cargo project.

Co-authored-by: GCOV Github Badge <build@github.com>

examples/rig-integration/Cargo.toml

@@ -16,6 +16,7 @@ rig-core = "0.10.0"
 tokio = { version = "1", features = ["full"] }
 rmcp = { path = "../../crates/rmcp", features = [
     "client",
+    "reqwest",
     "transport-child-process",
     "transport-sse-client",
 ] }