various fixes to dojox/mobile/bidi code:

1. fix accidental creation of "config" global variable
2. fix summary of config module to appear in API doc
3. don't use deprecated dijit/_BidiSupport module; use new dijit/_BidiMixin

refs #15778

(cherry picked from commit 55265d8c567b54ad57bcc029f5e3d225171871f7)
lightweight css loader
widget theme infrastructure

1. add themes/ directory based on dojox/mobile/themes, where LESS files in common/ are compiled into CSS
   for each theme.
	- old android theme removed in favor of holodark
	- iphone theme renamed to ios; currently there's no differentiation between iphone and ipad
	- compatibility files removed; hopefully we don't need them anymore since we just support newer browsers
	- adds placeholder "bootstrap" theme; it's just a copy of "custom" but should be changed to be a cross
	  platform theme
	- generated CSS stored in AMD modules for cross-domain loading (otherwise dui/css! would use dojo/text!)

2. dui/themes/load! plugin for widgets to automatically load their CSS based on page's theme; based loosely
   on deviceTheme.js
	- tests/boilerplate.js modified to not load CSS files since the widgets will do it automatically

3. ExampleWidget for testing LESS compilation and load! plugin
add tests for 17003
add TODO
Fixes #17417. IE11 support. Thanks Sebastien Brunot (IBM, CCLA)