Add support for class members #7479

Job	Run time
Build LPython to WASM	1m 20s
Test CPython Interop (@pythoncall)	3m 43s
Build Jupyter Kernel	3m 29s
LPython CI (3.10, ubuntu-latest)	7m 28s
Run Integration tests with Python 3.9	4m 3s
LPython CI (3.10, macos-latest)	7m 37s
Run Integration tests with Python 3.10	3m 54s
Check Debug build	4m 45s
LPython CI (3.10, windows-2019)	12m 30s
Check Release build	2m 3s
Run Integration tests with Python 3.11	3m 53s
Run Integration tests with Python 3.12	4m 7s
Run SymPy tests	4m 16s
Test LLVM 10	4m 34s
Test PIP Installable Packages	3m 25s
Test LLVM 15	4m 36s
Upload Tarball	40s
Test LLVM 16	4m 47s
	1h 21m 10s

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