Make mountsLock and authLock in Core configurable

[marcboudreau]

Description

This PR changes the mountsLock and authLock fields in the Core struct from locking.DeadlockRWMutex to locking.RWMutex. This change allows the fields to be set to either locking.DeadlockRWMutex or locking.SyncRWMutex (or any other type that fulfills the locking.RWMutex interface for that matter).

These fields are now set using the locking.CreateConfigurableRWMutex function which selects the locking.DeadlockRWMutex implementation if the provided lock type name is present in the provided detectDeadlocks slice.

The detect_deadlocks configuration parameter is used to specify which locks are configured to use the locking.DeadlockRWMutex. If a lock is not specified in that parameter, it is configured to use the locking.SyncRWMutex which is an alias for sync.RWMutex.

This PR has an accompanying ENT PR: https://github.com/hashicorp/vault-enterprise/pull/6163

TODO only if you're a HashiCorp employee

• Labels: If this PR is the CE portion of an ENT change, and that ENT change is
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  the normal backport/x.x.x label (there should be only 1).
• ENT Breakage: If this PR either 1) removes a public function OR 2) changes the signature
  of a public function, even if that change is in a CE file, double check that
  applying the patch for this PR to the ENT repo and running tests doesn't
  break any tests. Sometimes ENT only tests rely on public functions in CE
  files.
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  in the PR description, commit message, or branch name.
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• ENT PR: If this change has an associated ENT PR, please link it in the
  description. Also, make sure the changelog is in this PR, not in your ENT PR.

[github-actions]

CI Results:
All Go tests succeeded! ✅

[github-actions]

Build Results:
All builds succeeded! ✅

[raskchanky]