Pass new fuzz targets to docker containers at runtime

[oliverchang]

Rather than requiring us to patch Dockerfiles with an ADD instruction to add the fuzz target to the filesystem. This is rather hacky and has a lot of gotchas (see e.g. https://github.com/google/oss-fuzz-gen/pull/699)

This would be a lot cleaner and simplify a lot of our current infrastructure.

[oliverchang]

@DavidKorczynski @DonggeLiu

[abohoss]

Hi @oliverchang , Is this issue still open? I would love to work on it

[demoncoder-crypto]

Hi @oliverchang Check #959 for implementation and see if its up to expectation

[DonggeLiu]

@oliverchang could you please take a look at this at your convenience? Thanks!