There are currently no benchmarks for libmongocrypt's encryption implementation. We should add a benchmarking suite to guard against performance regressions in the underlying implementation relied upon by drivers that call into libmongocrypt. 

Acceptance Criteria

• Benchmark explicit encryption with each supported algorithm.
• Benchmark explicit decryption with each supported algorithm.
• Benchmark automatic encryption with each supported algorithm.
• Benchmark automatic decryption with each supported algorithm.

Benchmark only with the local KMS provider. libmongocrypt caches the decrypted Data Encryption Key (DEK). There is no expected benefit to testing other KMS providers.