Implement optional chaining #4192

Job	Run time
Linux_x86_cpointer-32bit_Build_Correctness_Tests	2m 7s
Conformance_Tests_ESNext	2m 11s
Conformance_Tests_ESNext_Debug_A	2m 20s
Conformance_Tests_ESNext_Debug_B	1m 20s
Checks	5m 15s
Linux_x86-64_Build_Correctness_Debugger_Tests	5m 17s
Linux_x86-64_Build_Option_Tests	4m 18s
OSX_x86-64_Build_Correctness_Unit_Tests	3m 39s
OSX_x86-64_Build_Correctness_Unit_Tests_Debug	3m 23s
ASAN_Tests_Debug	3m 23s
ASAN_Tests	3m 41s
Clang_Unit_Build_Option_Tests	4m 18s
Linux_AArch64_Tests	5m 13s
Linux_AArch64_Tests_Debug	6m 40s
Linux_ARMv7l_Tests	4m 5s
Linux_ARMv7l_Tests_Debug	5m 51s
MbedOS_K64F_Build_Test	1m 25s
NuttX_STM32F4_Build_Test	2m 19s
RIOT_STM32F4_Build_Test	1m 1s
UBSAN_Tests	2m 12s
Unit_Tests	1m 45s
Zephyr_STM32F4_Build_Test	3m 11s
ESP_IDF_Build_Test	3m 51s
ESP8266_RTOS_SDK_Build_Test	1m 33s
Notification	0s
	1h 20m 18s

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