Add autocommit parameter to transaction API

SERVER-33132 libdocument_source.so should not depend into logical_session_cache_impl.so

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• Closed

SERVER-33336 Snapshot reads should not take MODE_IX locks when autocommit=true

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• Closed

SERVER-32320 Push applyOps oplog entry generation into logOp on transaction commit

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• Closed

SERVER-32322 Allow doing a single update operation with deferred commit

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• Closed

SERVER-33423 Add unit-test coverage for autocommit parameter

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• Closed