feat: add lint warning for newline_eof

[simojoe]

This pull request adds a new rule to wdl.

• Rule Name: newline_eof
• Rule Kind: Lint warning
• Rule Code: v1::W007
• Packages: wdl-grammar

This rule is currently written as to avoid missing newline at the end of WDL files.

My interpretation of the rule is that a WDL file should not end with an empty line (double newline symbols), but the rule description is not explicit about that (or the opposite situation).

The implementation currently checks two things :

• there is at least one newline at the end of the file
• there is at most one newline at the end of file

Let me know if this implementation is not suitable

Before submitting this PR, please make sure:

• You have added a few sentences describing the PR here.
• You have added yourself or the appropriate individual as the assignee.
• You have added at least one relevant code reviewer to the PR.
• Your code builds clean without any errors or warnings.
• You have added an entry to the relevant CHANGELOG.md (see
  ["keep a changelog"] for more information).
• Your commit messages follow the [conventional commit] style.
• Your changes are squashed into a single commit (unless there is a really
  good, articulated reason as to why there shouldn be more than one).

Rule specific checks:

• You have added the rule as an entry within the the package-specific rule
  tables (wdl-ast/src/v1.rs for AST-based rules and
  wdl-grammar/src/v1.rs for parse tree-based rules).
• You have added the rule as an entry within the the global rule
  table at RULES.md.
• You have added the rule to the appropriate fn rules().
  • Validation rules added to wdl-ast should be added to fn rules() within
    wdl-ast/src/v1/validation.rs.
  • Lint rules added to wdl-ast should be added to fn rules() within wdl-ast/src/v1/lint.rs.
  • Validation rules added to wdl-grammar should be added to fn rules() within
    wdl-grammar/src/v1/validation.rs.
  • Lint rules added to wdl-grammar should be added to fn rules() within
    wdl-grammar/src/v1/lint.rs.
• You have added a test that covers every possible setting for the rule
  within the file where the rule is implemented.

[simojoe]

Updated the PR.

The only thing that I am unsure about is for Gauntlet.

I am running cargo run --bin wdl-gauntlet -- --save-config to generate the Gauntlet.toml file, but I am getting stuck behind the rate limit. Is there a way that I can use my personal GitHub account to fill the repository cache for wdl-gauntlet ?

[peterhuene]

@simojoe FYI, you may set the GITHUB_TOKEN environment variable to a personal GitHub access token, which should help getting pass the rate limiting.