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

[maschad]

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 libp2p/js-libp2p#1505 (comment) for more context