Migrate bytecode comparison from Travis to CircleCI

[cameel]

Related to #9258. Would also probably solve #4044.

Right now the bytecode comparison script runs on TravisCI (https://github.com/ethereum/solidity/blob/v0.7.2/.travis.yml#L208). We want to move away from Travis and move it to CircleCI.

When we move everything off Travis we'll be able to take away its write permissions to solidity repo/releases.

[cameel]

Notes from the call today:

• Bytecode comparisons are not a part of the release process so they do not introduce a delay there, unlike the binary builds (Move release binary builds off Travis #9932).
• The biggest issue with having it in Travis is that we can only do the check after the merge to develop.
• Apart from just moving it, we also want to change the way it works:
  • The generated bytecode should be an artifact in CircleCI.
  • There should be a job that depends on all the jobs that produce bytecode for specific platforms and compares it. This way we can get rid of the solidity-test-bytecode repo.

[chriseth]

Bytecode comparison is on circleci now.

[cameel]

Just for future reference, it was implemented in this PR: #10039.