Changes to support project create view errors

[agjohnson]

There are a number of changes in this PR:

• Adds support for private repositories to the KO view, the form previously only supported community project creation and gave an error "Private repositories are not supported".
• Adds error fields for automatic and manual project creation tabs
• Disables most of the form if there are errors. The user can still see the disabled UI to give more context into what is happening
• The automatic tab UI was moved to a separate template because the parent template was getting very complex.

Also:

• Fixes #246
• Fixes #257
• Depends on https://github.com/readthedocs/readthedocs.org/pull/11095

[agjohnson]

Here's an example so far. I am aiming to retain the underlying UI in a disabled state so that there is a bit more visual context on what the UI normally does when not disabled.

[agjohnson]

https://github.com/readthedocs/readthedocs.org/pull/11135 is required here, I think I missed some logic that I added here at some point.

[agjohnson]

I feel this is ready to merge with the additional PR above merged in first.

[humitos]

Go for it! 👍🏼