Fix typos and inconsistencies for HEAD

Hello hackers,

Please consider fixing the next bunch of typos and inconsistencies in
the tree:
4.1. AccesShareLock -> AccessShareLock
4.2. AdjustTimestampForTypemod -> AdjustTimestampForTypmod
4.3. AExprConst -> AexprConst
4.4. AlterExtensionOwner_oid - remove (orphaned after 994c36e0)
4.5. AlterTableDropColumn -> ATExecDropColumn (renamed in 077db40f)
4.6. ApplySortComparatorFull -> ApplySortAbbrevFullComparator
4.7. arracontjoinsel -> arraycontjoinsel
4.8. ArrayNItems -> ArrayGetNItems
4.9. ArrayRef -> SubscriptingRef (renamed by 558d77f2)
4.10. AtPrepare_Inval - remove (orphaned after efc16ea52)

4.11. AttributeOffsetGetAttributeNumber - > AttrOffsetGetAttrNumber
4.12. AttInMetaData -> AttInMetadata
4.13. AuthenticationMD5 -> AuthenticationMD5Password (for the sake of
consistency with the docs)
4.14. AUTH_REQ_GSSAPI -> AUTH_REQ_GSS
4.15. autogened -> autogenerated
4.16. BarrierWait -> BarrierArriveAndWait()
4.17. bgprocno -> bgwprocno
4.18. BGW_NVER_RESTART -> BGW_NEVER_RESTART
4.19. BloomInitBuffer -> BloomInitPage
4.20. br_deconstruct_tuple -> brin_deconstruct_tuple

4.21. brin_tuples.c -> brin_tuple.c
4.22. bt_parallel_done -> _bt_parallel_done
4.23. bt_parallel_release -> _bt_parallel_release
4.24. btree_insert_redo -> btree_xlog_insert
4.25. bucket_has_garbage -> split_cleanup
4.26. byta -> bytea
4.27. CachePlan -> CachedPlan
4.28. CheckBufferLeaks -> CheckForBufferLeaks
4.29. check_for_free_segments -> check_for_freed_segments
4.30. chunkbit -> schunkbit

4.31. cking -> remove (the comment is old and irrelevant since PG95-1_01)
4.32. ClearPgTM -> ClearPgTm
4.33. close_ - > closept_
4.34. CloseTransient File -> CloseTransientFile
4.35. colorTrigramsGroups -> colorTrigramGroups
4.36. combinedproj -> remove (orphaned after 69c3936a)
4.37. contigous_pages -> contiguous_pages
4.38. cookies_len -> cookies_size
4.39. cost_tableexprscan -> remove (not used since introduction in fcec6caa)
4.40. create_custom_plan -> create_customscan_plan

4.41. CreateInitialDecodingContext -> CreateInitDecodingContext
4.42. CreateSlot -> CreateSlotOnDisk
4.43. create_tablexprscan_path -> remove (not used since introduction in
fcec6caa)
4.44. crypt_des -> px_crypt_des
4.45. ctrigOid -> trigOid
4.46. curCollations -> colCollations
4.47. cur_mem & prev_mem -> cur_em & prev_em
4.48. customer_id_indexdex -> customer_id_index
4.49. custom_scan -> cscan

I've split proposed patch to make the fixes checking simpler.

Best regards,
Alexander