Replacing alert box with modal ui

[vershwal]

Related #4806 #4977.

[bhousel]

Hey @vershwal this is good! I made some changes and merged it..

Here are some of the things I changed:

• I moved the whole thing into a new subfolder modules/ui/settings. What you built was really good and I realized that we are going to add a bunch more modal settings screens just like this one (for example to customize the vector tile and other data layers). So this gives us a place to organize them.
• There is another special kind of uiModal called uiConfirm, which already has an OK button, so I used that one. It makes the code a bit simpler..
• Dispatch a change event instead of trying to call a function back in uiBackground
• Add utilNoAuto to the textarea (this just prevents autocomplete and other annoying behaviors especially in Safari)

[vershwal]

Thanks, @bhousel!! Just saw the UI, looks great!!
There were many new things involved in this issue...Enjoyed doing this!!! If you find any other similar issue please tag me.