Feature flag to enable QUIC for custom CAs

Description

Adding a new feature flag to enable QUIC for sites served using certificates signed by a locally trusted custom CA

Who's implementing?

• I'm willing to implement this feature myself

The problem

In default Chromium, QUIC is explicitly disabled for sites served with a certificate signed with a custom CA even if it's trusted.

Discussion here https://groups.google.com/a/chromium.org/g/proto-quic/c/aoyy_Y2ecrI/m/R-Mdl9noBAAJ?pli=1

Possible solutions

I'd like to add a flag to enable this (disabled by default to map the default chromium behavior)

Alternatives

No response

Additional context

I've already implemented a small patch which works, but I'm wondering if this is ok for the ungoogled-chromium feature criteria before submitting the PR