Redirects to initial url after authentication and cleans up auth code

[MrMugame]

Things this changes:

• This uses query parameters to redirect to the requested url after authentication. There are probably a 100 ways to implement this, hope this is ok. (Fixes #886)
• I also separated the logout into it's own route as I don't see a reason why it would be a query parameter.
• I also changed the .all and if else code into the proper honojs code and used a hono validator to validate the form data. in the auth route handler
• vscode also did some formatting, which changed the indenting of some blocks, which is why the diff looks kinda insane

[zefhemel]

Thanks for this. The reindent makes it a bit hard to check if no important logic changed, but I think we're good.