Re-generate RawScripts.purs during CI tests

[jstolarek]

We currently version offchain/src/TrustlessSidechain/RawScripts.purs and offchain/test/Test/PoCRawScripts.purs files inside the repository, even though these files are generated automatically by calling make update-scripts from the offchain directory. There are good reasons to have these files versioned (faster development, less dependencies for anyone wanting to build the off-chain), we should have the CI test that these files build correctly and are up to date. Hence the proposal that the CI:

1. Builds all of on-chain code
2. Removes both raw-scripts files.
3. calls make update-scripts in offchain
4. checks that generated files are identical to what is stored in the repository (in other words, the git tree should be clean)

If any of the above fails, the CI should fail.

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IOG Jira: https://input-output.atlassian.net/browse/ETCM-7837