Implemented basic classes #7352

Job	Run time
Build LPython to WASM	5m 50s
Build Jupyter Kernel	3m 28s
LPython CI (3.10, ubuntu-latest)	8m 47s
Test CPython Interop (@pythoncall)	1m 31s
Check Debug build	2m 31s
LPython CI (3.10, macos-latest)	7m 38s
Run Integration tests with Python 3.9	1m 41s
LPython CI (3.10, windows-2019)	13m 3s
Run Integration tests with Python 3.10	1m 36s
Run SymPy tests	2m 1s
Check Release build	2m 29s
Run Integration tests with Python 3.11	1m 36s
Run Integration tests with Python 3.12	1m 34s
Test PIP Installable Packages	1m 23s
Upload Tarball	40s
	55m 48s

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