In mongocrypt-marking.c, the function _mongocrypt_fle2_placeholder_to_find_ciphertext() will need to be updated to support the v2 payload type.

In particular, the following changes are needed:

• the type of payload changes to mc_FLE2FindEqualityPayloadV2_t
• the ECCDerivedToken must be replaced by a ServerDerivedFromDataToken
• the derivation of the ServerDataEncryptionLevel1Token shall be removed. This token is no longer needed in the v2 payload.
• change calls to payload init/serialize/cleanup with v2 counterparts
• change the final serialized FLE2 subtype to MC_SUBTYPE_FLE2FindEqualityPayloadV2