Support github with data-residency

[davidkarlsen]

When using github with data residency the urls are:

• .ghe.com
• api..ghe.com

It would be great if this could be supported.

[caozhiyuan]

@davidkarlsen try this https://github.com/caozhiyuan/copilot-api
The enterprise version has not been tested yet, and minor adjustments may be needed if issues arise.