[clang] [clang-format] Change BinPackParameters to an enum to add a BreakAlways (PR #101882)

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VolatileAcorn wrote:

> If adding Leave is not trivial, we can support it in another patch.

I couldn't see a simple way to implement Leave, but it's possible I've missed something.

> Have you given any thought about [#53190 (comment)](https://github.com/llvm/llvm-project/issues/53190#issuecomment-1973631975)?

If BinPackArguments was also to be converted to an enum then yes I think it would make sense to update BAS_AlwaysBreak and BAS_BlockIndent, but if it is done now then I think it could be seen as inconsistent / confusing.
My thinking for this PR was to keep it constrained to what seemed like one of the more requested changes which was always breaking parameters and some of the other requests could be done as separate patches to make it more manageable.

https://github.com/llvm/llvm-project/pull/101882