[Feature] Improve curl based installation

[mehfuzh]

What

Implement a Pex-based solution for curl installaiton

Why

A PyInstaller-based solution is slow; a better alternative is PEX

How

Update the slp.spec to use PEX

Alternatives

NA

Additional Context

Reference:
https://pex.readthedocs.io/en/v2.1.39/buildingpex.html