dojox.mobile.parser should support data-dojo-mixins

[ykami]

data-dojo-mixins was introduced in dojo.parser (#14342). Mobile applications also need this functionality.

[ykami]

In [27729]:

Fixes #14716 !strict Added support for data-dojo-mixins, which is the same function as the one in dojo.parser (#14342). Renamed args to options.

[bill]

In [28094]:

Store parser's lowercase --> mixed case map as property of each widget's constructor, rather than in a global _nameMap[] hash.

This is necessary for #14960, since the constructor may have no string ID, and also fixes a subtle bug with the data-dojo-mixins feature #14716: for a node with data-dojo-type="A" and data-dojo-mixins="B, C, D", the parser was still doing a lookup as _nameMap[A], thus not finding the mixed-case methods from B, C, D.

Refs #14716, #14960 !strict.