feat: add check for proper snake_case usage

This commit squashes together the following commits:

* feat: adding Naming lint gorup
* feat: adding snake-case rule
* feat: renaming lint rule
* doc: adding rule to RULES.md
* test: adding more test-cases
* docs: updating documentation
* chore: updating wdl-grammar changelog
* chore: update PR number in changelog
* feat: adding test and doc for snake_case lint warning
* feat: updating Gauntlet.toml for snake_case
* chore: updates `gauntlet` configuration

Cargo.toml

@@ -17,6 +17,7 @@ version = "0.2.0"
 [workspace.dependencies]
 clap = { version = "4.4.7", features = ["derive"] }
 colored = "2.0.4"
+convert_case = "0.6.0"
 env_logger = "0.10.0"
 indexmap = { version = "2.1.0", features = ["serde"] }
 lazy_static = "1.4.0"