Feature/bare2share: implement redirect anonymous bare url to /share page

[maphew]

addresses #658 Adds Options >> Other >> Share Settings:

• Added a simple checkbox to enable/disable bare domain redirect to /share
• "Show login in share theme" option

---

Some of the intemediate commits use custom urls for both Share and Login. I rolled back because was getting too complicated. For example, what if user defined urls that are already used by existing routes? We'd need to add path validation and probably other stuff too.

My motivation was to obscure the login link in order to provide a little protection from simple bot attacks. It's likely better to take a considered security look (from folks who know this space!)

[perfectra1n]

I understand about the motivation - but security through obscurity doesn't count for much unfortunately. Definitely a cool idea though, I dig the effort 💪

[maphew]

current code is not working. :-/ converted to draft. Somehow what I committed differs from what I had running and working. I'm tracking that down now.

[maphew]

Cleaned up and believed ready for review.