fix(no-implicit-declare-namespace-export): skip declare global

[fibibot]

Summary

• declare global { ... } is a module augmentation, and TypeScript rejects both export {} and export { ... } inside one (TS2669 / "Exports and export assignments are not permitted in module augmentations").
• The current no-implicit-declare-namespace-export rule fires on a declare global block and suggests export {};, but following that hint swaps the warning for a real TypeScript compile error — so the rule just makes declare global augmentations unlintable without an ignore pragma.
• Skip TsModuleDecl nodes where module_decl.inner.global is true (SWC's flag for declare global).

Refs denoland/deno#33268.

Repro (before this PR)

// error: Implicit exports in ambient namespaces are discouraged to use
//   Try adding an `export {};` to the top of the namespace to disable this behavior
declare global {
  const asdf: number;
}

// Following the hint just creates a TypeScript error:
declare global {
  export {};   // TS2669: Exports and export assignments are not permitted in module augmentations.
  const asdf: number;
}

Test plan

• Extended use_explicit_namespace_export_valid with two declare global { ... } fixtures (one with a const, one with interface + const). Verified they fail the previous assertion and pass with this change.
• cargo test no_implicit_declare_namespace_export clean.
• cargo test full suite clean.
• deno run --allow-run ./tools/format.ts --check clean.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}