Add option to exclude sol files from being packed to ContractRegistry

[3Nigma]

Oftentimes you would want to exclude certain sol files from being reflected by the ContractRegistry ABI records. This is especially the case if you have so-called mocked-contracts whos only purpose is to aid in testing and should not or, due to import resolution concerns, are impossible to have their ABI generated.

Therefore, it would be nice if the venin-rollup-plugin would allow us to exclude sol files that match certain pattern matching criterion.

Thus, the options object passed to the rollup-plugin would need to be augmented with the following:

• contracts.path can be a string in which case, the behavior of the ContractRegistry crawler remains the same or
• contracts.path can be a json object with the following schema:
  • root : the base path to start loading the contracts from (identical to the contracts.path that's available before this ticket is implemented)
  • ignore: a picomatch path specifier which, if a sol files truth-ly matches against it, the file is dropped and won't be parsed into the resulting ContractRegistry

We would need to extend the test-base (add jest?) to accommodate this feature.