Unified method style

[alan-george-lk]

This PR addresses the following:

• Through an audit of the current state of the repo, the vast majority of functions/methods were lower camel-case styling (AKA camelBack()). Some were PascalCase and snake_case
• Moving from this PR forward, all functions/methods should be camelBack() case
  • Public headers: methods that violate this rule are duplicated, old ones kept and marked [[deprecated]], such that we have some time to fix other references (examples) prior to release
  • Internal header symbols were updated outright (no duplication/deprecation needed)
  • Unit tests/docs/etc. updated
• clang-tidy now enforces this and will fail builds that violate this

Note: the current plan is to drop the old style deprecated methods for 1.0.0 release. This PR doesn't attempt that just yet

This also addresses a regression in participant.h:

• Previously had set_* methods (plain member variable setters)
• Conflicted with local_participant.h versions of the same name after method unification
• Decision: Now those base methods are removed, and room.h is now a friend class and can directly modify those variables. Matches Python SDK equivalent

[stephen-derosa]

LGTM!

[xianshijing-lk]

lgtm assuming you address the noexcept