MINIFICPP-2462 - Divide libminifi

[adamdebreceni]

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[lordgamez]

A few additional comments we talked about in person that should be done afterwards in different PRs and should create separate Jira tickets for:

• we should add Impl suffix to core/* files in future
• Move core/include/minifi-cpp directory minifi-api/include/minifi-cpp-api and later have a separate minifi-c-api directory for C API
• remove ThreadedRepository.h from minifi api and replace its usage with core::TraceableResource

[martinzink]

I've started to implement my new PR-s on top of this.
Dont want to further increase the size of the PR with nitpicks (since you touched almost the whole codebase I think we can skip the clang-tidy fixes aswell)
Great work LGTM 👍 please rebase and fix the rebase issues

[szaszm]

first bunch

[szaszm]

two more missing line endings from the end, but otherwise it looks fine