[Enhancement] Add FIPS enabled docker to test digest/signature correctly

[peterzhuamazon]

After #2099 closed we now have these setups for rpm:

1. Sha1/Sha256 digest for header
2. Sha256 digest for payload
3. Sha512 signature for both header and payload

This requires us to generate the RPM on rpm 4.12+ available machine, and #2113 fix that one already.

Next step is to add testing once the signing workflow is updated to be able to sign staging RPMs.

We need:

1. Exchange the RPM validation docker image from centos7 to a rockylinux8 based FIPS enabled machine, require new dockerfile and more research on how to enable FIPS on a docker image
2. Add test cases in RPM validation for these checks with rpm -K -v <>.

Thanks.

[peterzhuamazon]

• Make rpm build on centos7 and assemble on rockylinux8 to generate digest correctly for FIPS-enabled nodes #2113
• Add rockylinux8 build related image for building rpm #2122

[peterzhuamazon]

Realize that non-FIPS enabled machine can also check digests as long as it is on a FIPS-capable machine like Rockylinux8.
Close this.