C#: make keywords static to avoid allocations #2589

Job	Run time
Check	1m 54s
Rustfmt	4s
Test (ubuntu-latest, c)	4m 19s
Build wit-bindgen (x86_64-linux, ubuntu-latest)	1m 36s
Test (ubuntu-latest, rust)	4m 42s
Crate Unit Tests	1m 0s
verify-publish	1m 47s
Build wit-bindgen (x86_64-macos, macos-latest, x86_64-apple-darwin)	1m 35s
Test (ubuntu-latest, teavm-java)	5m 2s
Build wit-bindgen (aarch64-macos, macos-latest, aarch64-apple-darwin)	1m 47s
Build wit-bindgen (x86_64-windows, windows-latest)	3m 43s
Test (ubuntu-latest, go)	5m 37s
Test (ubuntu-latest, csharp)	7m 52s
Build wit-bindgen (aarch64-linux, ubuntu-latest, aarch64-unknown-linux-gnu)	1m 38s
Test (macos-latest, c)	5m 6s
Test (macos-latest, rust)	3m 34s
Test (macos-latest, teavm-java)	4m 20s
Test (macos-latest, go)	6m 59s
Test (macos-latest, csharp)	5m 0s
Test (windows-latest, c)	8m 5s
Test (windows-latest, rust)	9m 5s
Test (windows-latest, teavm-java)	8m 24s
Test (windows-latest, go)	11m 44s
Test (windows-latest, csharp)	30m 50s
Record the result of testing and building steps	1s
	2h 15m 44s

Provide feedback