fix(test): exclude the cwd-exclusion pair from the Node and Bun runners - #3500

Both runners decide whether a test is Deno-only by reading that file's own
source for `Deno.`. The cwd-exclusion pair keeps its Deno usage in the helper
it imports, so the heuristic missed it and `deno task test:node` began failing
on `Deno.chdir` being undefined.

Named explicitly rather than by making the files mention `Deno.` to satisfy the
heuristic: the pair asserts a property of `deno test --parallel` itself -- that
test files sharing one process do not share a working directory -- so it is
Deno-only by subject and not merely by which API it happens to call.

CI runs neither task, which is why this survived review.

The reviewer asked for coverage on both runners' filters, which the exclusion
had none of: it was a literal in each runner, duplicated, and nothing noticed
if it stopped matching. Renaming the pair or moving it out of `src/testing/`
would leave a pattern matching nothing and `deno task test:node` would fail
again, which is the regression this list was added for.

The patterns move to `tests/deno-only-tests.mjs`, imported by both runners so
they cannot drift, and `tests/runtime-test-filters.test.ts` asserts both
directions: the pair is excluded, and its neighbours -- including
`cwd.test.ts`, which shares a prefix -- stay eligible. Both halves matter; a
filter that excludes too much shrinks the suite silently. Checked against a
list emptied and a pattern widened, and it fails on each.

Also fixes an unrelated Deno-only import that made `deno task test:bun` fail
before it reached any of this: `extensions/ext-bundler-esbuild` wrote
`npm:es-module-lexer@2.3.1` inline while its own deno.json already maps the
bare specifier, as it does for esbuild. Only Deno resolves the inline form.