fix(linter): add help text to more eslint rule diagnostics

[anthonyamaro15]

PR covers:

Closes #19121 (partially)

Add .with_help() to 5 more ESLint rule diagnostics:

• no-async-promise-executor: "Remove the async keyword from the Promise executor function."
• no-undefined: "Avoid using undefined directly as an identifier. Use null instead."
• no-class-assign: "Use a different variable name instead of re-assigning the class declaration."
• no-global-assign: "Use a local variable instead of modifying the global '{global_name}'."
• no-throw-literal: "Throwing literals or non-Error objects is not recommended. Use an Error
  object instead."

5 rule files changed + 5 corresponding snapshot updates.

[Copilot]

Pull request overview

This PR adds helpful diagnostic messages to 5 ESLint rules that previously lacked them, partially addressing issue #19121. The changes provide users with actionable guidance on how to fix linting violations.

Changes:

• Added .with_help() to 5 ESLint rule diagnostics with clear, actionable guidance
• Updated corresponding snapshot files to reflect the new help text

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/oxc_linter/src/rules/eslint/no_async_promise_executor.rs	Added help text instructing users to remove the async keyword
crates/oxc_linter/src/rules/eslint/no_undefined.rs	Added help text about avoiding undefined identifier (contains an error)
crates/oxc_linter/src/rules/eslint/no_class_assign.rs	Added help text suggesting a different variable name
crates/oxc_linter/src/rules/eslint/no_global_assign.rs	Added help text recommending use of local variables
crates/oxc_linter/src/rules/eslint/no_throw_literal.rs	Replaced specific fix instructions with generic educational help text (appropriate for conditional_suggestion rules)
crates/oxc_linter/src/snapshots/eslint_no_async_promise_executor.snap	Updated snapshot to reflect new help text
crates/oxc_linter/src/snapshots/eslint_no_undefined.snap	Updated snapshot to reflect new help text
crates/oxc_linter/src/snapshots/eslint_no_class_assign.snap	Updated snapshot to reflect new help text
crates/oxc_linter/src/snapshots/eslint_no_global_assign.snap	Updated snapshot to reflect new help text
crates/oxc_linter/src/snapshots/eslint_no_throw_literal.snap	Updated snapshot with generic help text replacing specific fix instructions

[codspeed-hq]

Merging this PR will not alter performance

✅ 47 untouched benchmarks
⏩ 3 skipped benchmarks¹

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_{Comparing anthonyamaro15:fix/eslint-diagnostics-add-help-text-3 (642b612) with main (f398bc9)²}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (d7b63a4) during the generation of this report, so f398bc9 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[camc314]

Thank you!