Support mjs and cjs files in Static Reachability

What does this MR do and why?

Resolves Support .mjs and .cjs files for static reachabi... (gitlab-org/gitlab#555400 - closed).

.mjs and .cjs should be supported out-of-the-box by our current SR capabilities, as they are contained within JavaScript which SR supports.

This MR adds .cjs and .mjs to the list of files collected by SR for JavaScript analysis.

We should identify some projects that contain .mjs and .cjs files to verify this change on.

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