[Feat]: Add support for GitHub Enterprise Server (GHES)

[MoshiBin]

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Is your feature request related to a problem? Please describe. I'd like to connect my on-prem GHES instance to lowcoder.

Describe the solution you'd like When adding GitHub as a Data Source, allow me to provide my own server URL instead of api.github.com

Describe alternatives you've considered Can't think of an alternative.

Additional context None.