Fix various typos and grammar errors in comments.

src/backend/access/brin/brin_tuple.c

src/backend/access/nbtree/nbtree.c

src/backend/access/transam/twophase.c

src/backend/catalog/objectaddress.c

src/backend/commands/indexcmds.c

src/backend/executor/nodeModifyTable.c

src/backend/postmaster/bgworker.c

src/backend/replication/logical/snapbuild.c

src/backend/storage/lmgr/lwlock.c

src/backend/utils/cache/inval.c

src/bin/pg_archivecleanup/pg_archivecleanup.c

src/bin/pg_basebackup/pg_recvlogical.c

src/bin/pg_upgrade/parallel.c

src/bin/pg_upgrade/relfilenode.c

src/include/access/attnum.h

src/include/access/xact.h

src/include/mb/pg_wchar.h

src/include/storage/s_lock.h

src/interfaces/ecpg/pgtypeslib/datetime.c

src/interfaces/ecpg/pgtypeslib/numeric.c