tfsdklog: Introduce outside context level checks for logging functions

[bflad]

Reference: hashicorp/terraform-plugin-framework#721

This change introduces log level checks outside the context.Context of a request to improve the performance of logging functions when logs would not be emitted at the configured level. Almost exclusively, logging levels are not expected to change during provider (and therefore SDK) runtime since they are environment variable driven. Even if they did, this level check will either immediately constrict logging to match an updated higher level or cause additional context.Context reads with an updated lower level, which is no different than the current behavior.

The following benchmark was ran prior to the introduction of the level checks and mutexes:

BenchmarkSubsystemTraceDisabled-10            4616656               258.0 ns/op
BenchmarkSubsystemTraceEnabled-10              936865              1138 ns/op

After the addition of level checks and mutexes:

BenchmarkSubsystemTraceDisabled-10           86043471                13.78 ns/op
BenchmarkSubsystemTraceEnabled-10              906649              1137 ns/op

This enhancement could also be considered for provider loggers, however SDK logging tends to be more prevalent in practice, so this only targets the tfsdklog package handling.

[austinvalle]

syntactically looks good 👍🏻 , will be interesting to hear how the performance improves from the original issue

[bflad]

We haven't heard back from the original reporter for awhile now, but we'd also like to cut a framework release. I'm going to optimistically merge this in so we can cut a release of this module and update the dependency in terraform-plugin-framework, then we can reassess things afterwards.

[github-actions]

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