Added jerry-ext amalgamation (#5184) #4291

Job	Run time
ASAN_Tests_Debug	3m 29s
ASAN_Tests	3m 27s
Clang_Unit_Build_Option_Tests	4m 10s
Checks	5m 29s
Conformance_Tests_ESNext	2m 5s
Conformance_Tests_ESNext_Debug_A	2m 6s
Conformance_Tests_ESNext_Debug_B	1m 16s
ESP_IDF_Build_Test	3m 31s
ESP8266_RTOS_SDK_Build_Test	1m 33s
Linux_AArch64_Tests	4m 25s
Linux_AArch64_Tests_Debug	6m 26s
Linux_ARMv7l_Tests	4m 23s
Linux_ARMv7l_Tests_Debug	6m 2s
Linux_x86_cpointer-32bit_Build_Correctness_Tests	1m 38s
Linux_x86-64_Build_Correctness_Debugger_Tests	5m 8s
Linux_x86-64_Build_Option_Tests	4m 15s
MbedOS_K64F_Build_Test	1m 24s
Notification	0s
NuttX_STM32F4_Build_Test	2m 9s
OSX_x86-64_Build_Correctness_Unit_Tests	3m 44s
OSX_x86-64_Build_Correctness_Unit_Tests_Debug	3m 4s
RIOT_STM32F4_Build_Test	52s
UBSAN_Tests	2m 46s
Unit_Tests	1m 45s
Zephyr_STM32F4_Build_Test	3m 19s
	1h 18m 26s

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