Add customizable homepage

[Chickaboo]

Introduces a new customizable new tab page with clock, greeting, and search bar. Adds settings for enabling/disabling the homepage, choosing between default or custom URL, toggling clock and greeting, and selecting time format. Implements new internal protocols for 'min://newtab' and 'min://blank', updates localization, and refines related CSS and JS for the new tab and settings pages.

[PalmerAL]

Thanks for the PR!

I think it makes sense to have a setting to set a custom new tab URL. I'm less convinced that we should have a built-in page. My impression is that there are a lot of potential designs for a new tab page, and people tend to have strong opinions about which design is the best for them; designing something that makes most people happy would require a ton of different customization options and add a lot of complexity.

How would you feel about keeping just the setting to set a custom URL, and putting any specific page designs in an external repository?

Also, it would be good to figure out a better interaction between the NTP and the searchbar. When I open a new tab, I don't actually see the NTP, because the searchbar is covering it:

I think this should probably work like this (what do you think?):

1. When you open a new tab, the searchbar is active and focused, but if a custom NTP is configured, no suggestions are shown underneath.
2. The NTP is immediately visible.
3. If you start typing in the searchbar, we start showing the searchbar suggestions and blur the NTP.

[PalmerAL]

Also, I should point out, we already have an option to set a custom image background on the new tab page:

We should ensure any changes are compatible with that.

[Chickaboo]

That sounds good to me. I'll remove the new tab page and make it so that in the settings, you can choose either the NTP or a custom URL. A better implemetion of the NTP and the search bar interaction is something I will look into. I think the outline you gave will work well. I'll try to work on this sometime soon, but it might be a week or two.