docs: Run `dep-check` on TS snippet imports

**Is your feature request related to a problem? Please describe.**

The `doc-check` command compiles Typescript snippets in Markdown files but it would also be nice to run `dep-check` on those imports.

**Describe the solution you'd like**

Modify the `dep-check` command to check _imports_ in TS snippets in markdown and run this as a part of `doc-check`

See https://github.com/libp2p/js-libp2p/pull/1505#issuecomment-1612153921 for more context