fix(cli/tsc): use Blob to detect web fetch globals in node/globals.d.cts

[fibibot]

Summary

The vendored @types/node globals.d.cts uses typeof globalThis extends { onmessage: any } to decide whether to fall back to undici's web fetch types. Deno only exposes onmessage on globalThis inside worker contexts, so in regular Deno code the LSP picks the undici types. As a result, otherwise-valid code like

const init: Parameters<typeof fetch>[1] = {};
const req = new Request("https://deno.com", init);

is rejected by the LSP with Argument of type 'global.RequestInit' is not assignable to parameter of type 'RequestInit', even though deno check passes.

This switches the discriminator from onmessage to Blob. Blob is part of Deno's stable web platform globals, so the conditional now correctly picks {} (deferring to Deno's own globals) instead of falling back to undici.

This was previously attempted in #33037 directly editing globals.d.cts. That PR was closed because the file is vendored and gets overwritten by tools/update_types_node.ts. This PR also wires the rewrite into the update script so the next @types/node sync preserves it.

Closes #33012.

Test plan

• Updated globals.d.cts to use the Blob discriminator
• Added a programmatic rewrite step in tools/update_types_node.ts so future regens preserve the change
• New LSP regression test lsp_request_init_global_matches_check opens the issue's repro and asserts no diagnostics
• cargo test -p integration_tests --test integration lsp_request_init_global_matches_check passes locally
• deno check on the issue's repro file passes