SERVER-14099 Add GroupStage query execution stage

getExecutorGroup() is now the main entry point for execution of a
group operation.
SERVER-14099 Add explain command support for group
SERVER-13635: move some tests that mmap specific
SERVER-13635: add check that storage engine returns valid DiskLoc
SERVER-13635: fix captrunc transaction nesting
SERVER-13635: fix transaction nesting
SERVER-13635: tailable test for heap
SERVER-13635: BSONCollectionCatalogEntry supports options
SERVER-15156 skip _id index checks on the config db in the upgradeChecker()
SERVER-15189 remove calls to recordPing() and updateHeartbeatData() from TopologyCoordinator testing
SERVER-15189 remove recordPing() and updateHeartbeatData() methods from the TopologCoordinatorImpl
SERVER-14668 remove no-OpCtx DBDirectClient and update all former users
SERVER-15180 Fix typos in lock manager tests and a heap1 error message

Closes #768

Signed-off-by: Benety Goh <benety@mongodb.com>
SERVER-15151: use isSelf on Windows, Solaris, & FreeBSD
SERVER-15190 Report detected libdeps cycles
SERVER-15159 Cleanups for awaitReplication in ReplicationCoordinatorImpl
SERVER-15188 all lastOpTimeWritten setting goes through the legacy repl coord