Add new flavor definition style, add bioinformatics flavor

[nwiltsie]

This is a somewhat provocative PR that does two things - no hard feelings if you reject either or both changes.

Proposed Changes

1. Add logic to respect descriptors and linters entries in flavor info returned from megalinter.flavor_factory.list_megalinter_flavors()
   • It feels very non-DRY to have each descriptor list all the flavors that include it, rather than having each flavor list the descriptors it includes.
   • I've added logic so that the flavor information dicts returned from list_megalinter_flavors() can include pre-filled descriptors and linters lists. That seems to allow a flavor to be completely defined within flavor_factory.py.
2. Add a new bioinformatics flavor.

Based on local testing this seems to work as expected - the bioinformatics Dockerfile builds and runs appropriately, and bioinformatics appears as a new flavor (including being linked from each "This linter is available in the following flavors" section).

From the outside this seems like a cleaner way to define flavors, but I easily could be missing some critical reason why the current method is necessary.

Readiness Checklist

Author/Contributor

• Add entry to the CHANGELOG listing the change and linking to the corresponding issue (if appropriate)
• If documentation is needed for this change, has that been included in this pull request

Reviewing Maintainer

• Label as breaking if this is a large fundamental change
• Label as either automation, bug, documentation, enhancement, infrastructure, or performance