Add support for base in `int()` #5927

Job	Run time
Check Debug build	3m 56s
Build LPython to WASM	8m 10s
Test CPython Interop (@pythoncall)	2m 21s
LPython CI (3.10, ubuntu-latest)	17m 13s
LPython CI (3.10, macos-latest)	23m 46s
Run Integration tests with Python 3.9	2m 26s
Check Release build	3m 39s
LPython CI (3.10, windows-2019)	33m 25s
Run SymPy tests	2m 31s
Run Integration tests with Python 3.10	2m 4s
Run Integration tests with Python 3.11	2m 8s
Test PIP Installable Packages	2m 5s
	1h 43m 44s

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