add dev tools to decode payloads and use crypt_shared

[kevinAlbs]

This PR adds tools into libmongocrypt to (hopefully) benefit development:

• call_crypt_shared.sh can process a command with the Crypt Shared library.
• decode_payload.sh can decode a BSON binary subtype 6 payload.

Sample usage

The README.md files describe more usage.

To decode a payload:

./tools/decode_payload.sh --json ADgAAAAQYQABAAAABWtpABAAAAAEYWFhYWFhYWFhYWFhYWFhYQJ2AAwAAAA0NTctNTUtNTQ2MgAA

Output

{
    "name": "FLE1EncryptionPlaceholder",
    "dump": {
        "a": 1,
        "ki": {
            "$binary": {
                "base64": "YWFhYWFhYWFhYWFhYWFhYQ==",
                "subType": "04"
            }
        },
        "v": "457-55-5462"
    }
}

To process a command with crypt_shared:

export CRYPT_SHARED_LIB_PATH
./tools/call_crypt_shared.sh --cmd ./tools/call_crypt_shared/tests/find.yml

Output

{
    "hasEncryptionPlaceholders": true,
    "schemaRequiresEncryption": true,
    "result": {
        "find": "test",
        "filter": {
            "value": {
                "$eq": {
                    "$binary": {
                        "base64": "A1gAAAAQdAACAAAAEGEAAgAAAAVraQAQAAAABBI0VngSNJh2EjQSNFZ4kBIFa3UAEAAAAAQSNFZ4EjSYdhI0EjRWeJASEHYAQOIBABJjbQAAAAAAAAAAAAA=",
                        "subType": "06"
                    }
                }
            }
        },
        "encryptionInformation": {
            "type": {
                "$numberInt": "1"
            },
            "schema": {
                "test.test": {
                    "escCollection": "enxcol_.test.esc",
                    "ecocCollection": "enxcol_.test.ecoc",
                    "fields": [
                        {
                            "keyId": {
                                "$binary": {
                                    "base64": "EjRWeBI0mHYSNBI0VniQEg==",
                                    "subType": "04"
                                }
                            },
                            "path": "value",
                            "bsonType": "int",
                            "queries": {
                                "queryType": "equality",
                                "contention": {
                                    "$numberLong": "0"
                                }
                            }
                        }
                    ]
                }
            }
        }
    }
}