[WIP] Site ID Fixes

[SchrodingersGat]

This PR is a work in process to fix / simplify the site URL / multi-site support for InvenTree.

This fixes a few bugs and addresses some shortcomings of how the "site_url" parameter is configured.

Additionally, multi-site support is now disabled by default (a "breaking" change but most users would not use this feature at all). Disabling multi-site support makes a lot of things much simpler...

• Fixes Email confirmation key missing domain #6133

TODO

• Add documentation around enabling multi-site support
• Update SSO documentation (much simpler with multi-site support disabled)

References

• Email confirmation key missing domain #6133
• Cannot define hostname as base url #5585

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[matmair]

@SchrodingersGat great improvement. Do you think adding site control to the admin view might be in-scope for this?

[SchrodingersGat]

Do you think adding site control to the admin view might be in-scope for this?

Do you mean the PUI admin view? Site control is already available in the Django Admin view

[matmair]

@SchrodingersGat yes, sorry that was not phrased optimal

[SchrodingersGat]

I do not see the value here - it would be a very small user set (if any) who are using multi-site support. There is still always the Django Admin site available if absolutely required to setup?

[matmair]

I think you are right, we can add it later