Implement reindex command

src/backend/access/index/istrat.c

src/backend/access/nbtree/nbtree.c

src/backend/access/transam/xact.c

src/backend/bootstrap/bootstrap.c

src/backend/catalog/heap.c

src/backend/catalog/index.c

src/backend/catalog/indexing.c

src/backend/commands/indexcmds.c

src/backend/commands/trigger.c

src/backend/commands/vacuum.c

src/backend/executor/execUtils.c

src/backend/executor/nodeIndexscan.c

src/backend/optimizer/util/plancat.c

src/backend/parser/gram.y

src/backend/parser/keywords.c

src/backend/postmaster/postmaster.c

src/backend/tcop/postgres.c

src/backend/tcop/utility.c

src/backend/utils/adt/regproc.c

src/backend/utils/cache/catcache.c