feat: adds check for tasks with no runtime block

[markjschreiber]

This pull request adds a new rule to wdl.

• Rule Name: missing_runtime_block
• Rule Kind: Lint warning
• Rule Code: v1::W005
• Packages: wdl-grammar

Describe the rules you have implemented and link to any relevant issues.

The rule will warn if a task doesn't contain a runtime{} block because this is likely to limit the portability of the task.

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.

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.

[claymcleod]

Here are some thoughts on the code and a few more thoughts outside of that.

• We discussed it internally, and we good with this lint being standalone. There is also the concept that some of the runtime keys should be specified (for instance, container is almost certainly required to be portable). Rather than pushing for that to be included in this lint, we propose that we make a separate lint later on that addresses these—that way, users can configure separately whether they want to check for runtime blocks (almost always) versus what particular keys they want to enforce checking.
• Sadly, I think runtime is going away in WDL 1.2. So it's just worth noting that, when we do end up updating to 1.2, this lint may actually need to change to a deprecation warning for runtime and a new one will need to take it's place for the new keys.
• If you would, go ahead and squash down your changes into one commit so I can see what the final commit added to the history will be. This will require a force push to your branch.

[claymcleod]

Also, I will just note here for myself: we need to add a CHANGELOG.md and guidelines for adding entries to the CHANGELOG.md when these PRs are created.

[markjschreiber]

Here are some thoughts on the code and a few more thoughts outside of that.

• We discussed it internally, and we good with this lint being standalone. There is also the concept that some of the runtime keys should be specified (for instance, container is almost certainly required to be portable). Rather than pushing for that to be included in this lint, we propose that we make a separate lint later on that addresses these—that way, users can configure separately whether they want to check for runtime blocks (almost always) versus what particular keys they want to enforce checking.

Agreed, more granular lint checks help with configurable checking and can give better messages and fix suggestions

• Sadly, I think runtime is going away in WDL 1.2. So it's just worth noting that, when we do end up updating to 1.2, this lint may actually need to change to a deprecation warning for runtime and a new one will need to take it's place for the new keys.

Yes, it will be deprecated and replaced with requirements so the content of this check will essentially move to a requirements check.

• If you would, go ahead and squash down your changes into one commit so I can see what the final commit added to the history will be. This will require a force push to your branch.

Will do!