Refactor: L1/L2AssetHandler constructor params

refactor: rm layerZeroEndpoint constructor param in L1AssetHandler
refactor: rm layerZeroEndpoint constructor param in L2AssetHandler
build: swap out TEST_LAYER_ZERO_ENDPOINT for MAINNET_LAYER_ZERO_ENDPOINT in L1AssetHandlerTest & associated behavior tests
build: swap out TEST_LAYER_ZERO_ENDPOINT for ARBITRUM_LAYER_ZERO_ENDPOINT in L2AssetHandlerTest & associated behavior tests
build: rm redundant & obsolete STORAGE_SLOT variables in L1/L2AssetHandlerTest
build: swap out TEST_LAYER_ZERO_CHAIN_ID_DESTINATION for DESTINATION_LAYER_ZERO_CHAIN_ID in L1AssetHandlerTest & associated behavior tests
build: swap out TEST_LAYER_ZERO_CHAIN_ID_DESTINATION for DESTINATION_LAYER_ZERO_CHAIN_ID in L2AssetHandlerTest & associated behavior tests

Insrt-Finance / insrt-v2-contracts