CSHARP-4944: Enable use of native crypto in libmongocrypt bindings

[adelinowona]

Description

Use libmongocrypt native crypto when available.

What's changing

• Bundle crypto-enabled libmongocrypt on Mac.
• On linux continue to bundle crypto-disabled libmongocrypt, but inform users to install the crypto-enabled libmongocrypt on their system and use the new environment variable LIBMONGOCRYPT_PATH to make it available to the driver. If LIBMONGOCRYPT_PATH is not set then we default to using the packaged crypto-disabled libmongocrypt.

Performance Results

Using crypto-disabled libmongocrypt:

Method	ThreadsCount	Mean	Error	StdDev	Median
BulkDecryptionUsingBinding	1	50.83 ms	0.975 ms	2.279 ms	49.70 ms
BulkDecryptionUsingBinding	2	71.34 ms	1.422 ms	3.090 ms	71.32 ms
BulkDecryptionUsingBinding	8	766.59 ms	23.535 ms	69.393 ms	776.18 ms
BulkDecryptionUsingBinding	64	5,575.51 ms	91.840 ms	85.907 ms	5,581.51 ms

Using crypto-enabled libmongocrypt:

Method	ThreadsCount	Mean	Error	StdDev
BulkDecryptionUsingBinding	1	22.03 ms	0.103 ms	0.096 ms
BulkDecryptionUsingBinding	2	22.89 ms	0.117 ms	0.104 ms
BulkDecryptionUsingBinding	8	30.69 ms	0.564 ms	0.554 ms
BulkDecryptionUsingBinding	64	201.37 ms	1.997 ms	1.559 ms