* added comments on transfer hooks

* added sort

* added clearApprovalsAndEmitTransferEvent

* added tokenBatchTransfer hooks

* added _batchTransferFrom and safe variants

* added ERC721ABatchTransferable extension and interface

* formatting

* added interface and ERC721ABatchTransferableMock

* added ERC721ABatchTransferable tests (wip)

* added approvalCheck

* fixed duplicate call

* comment

* fixed next initialized

* refactored lastInitPackedOwnership to use prevPackedOwnership

* comments

* ensured correctness of nextInitialized in slots of transferred token Ids

* renamed variables

* reverted to leave nextInitialized unchanged

* comment

* replace sort -> insertion sort

* bump: prettier-plugin-solidity

* prettier

* added prettier-ignore

* fixed nextTokenId in last array element

* tests wip

* refactor

* updated BatchTransferable mock and extension

* updated tests

* add approval tests

* lint

* lint fix

* restore original .prettierrc

* fix

* comments and refactor

* added _batchBurn

* added ERC721ABatchBurnable extension, interfaces and mock

* fixed _batchBurn

* fixed update of last tokenId + 1

* batchBurnable tests wip

* refactor

* fix

* add auto-clearing of consecutive ids and set `nextInitialized` to false

* batchTransfer tests refactor

* tests wip

* tests wip

* comments

* added extraData logic to batch mocks

* updated batch tests

* refactored ERC721A to use _updateTokenId

* wip

* comment

* Add ERC721ABatchBurnableMock (#450)

* change tokenIds in ascending order in test

* removal of unneeded internal functions

* prettier

* removed batch transfer logic

* changed _updateTokenId

* fixed mock

* fixed extension and mock

* fixed tests and cleaned unused functions in mock

* removed _updateTokenId

* minor gas optimizations

* comment

* optimize: avoid potential double read from storage

* removed bulkBurn from mock

* optimization: reset _packedOwnerships for initialized sequential IDs

* added tests for sequential ID clearing

* added test for tokenIds in strictly ascending order

* comment

* optimize: keep track of prevTokenOwner to bypass duplicated logic

* revert: resetting _packedOwnerships in initialized sequential IDs

* cleanup

* optimize: avoid potential double read from storage

* refactor _batchTransfer logic

* optimized and stacked not too deep

* optimize: removed unneeded exists() via getApproved

* removed unneeded functions and batchBurn