Custom TAL fixture mount

This directory is intentionally shipped as a mount point, not as a repository of private keys. Run the patch tool tools/generate_custom_fixture.py to create the test-only TAL, TA, RPKI objects, HTTPS CA/server certificates, RRDP files, and rsync module data below it.

The generated fixture contains baseline-v1, sync-hash-mismatch and baseline-v2 for snapshot / hash / delta tests, plus validation-expired, validation-max-length, validation-max-length-invalid, validation-roa-prefix-outside, validation-out-of-resource, validation-ca-over-resource, and validation-nonstandard for validation cases. Generated keys are test-only and must not be used in a production RPKI hierarchy.