Define the format and write up the suite configuration file for the new implicit multiversion suites

Details TBD

• source suite config - fixture definitions are being overridden at runtime for multiversion, which is unintuitive for users.
• task definition
• not multiversionconstants since it's not used just by multiversion
• evergreen_gen_multiversion_tasks
• mongod options that are specific to a version. Perhaps as top-level keys in the fixture part of suite configurations.

merge replica_sets_multiversion and sharding_multiversion

Add a resmoke_e2e test for a dummy multiversion test to verify this syntax works.