BHV-3181: Preserve default alignment when text has different directionality.

Issue
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When there is text present that has a different directionality (as determined by our checkRtl method) than the default directionality, the text is not aligned according to the original/default directionality.

Fix
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We preserve text alignment by setting `text-align: left` and `text-align: right` for LTR and RTL modes, respectively, in the control-specific styling. Additionally, the `checkRtl` method has been moved from `Marquee` into Enyo core to allow general access by any control (specifically `moon.BodyText` in this case).

I went through all the `Moonstone` samples and did not find any adverse affects from the forced text-alignment at the `moon` CSS class level. Specifically, `moon.Button` and `moon.GridImageItem` appeared to have their `text-align: center` styling preserved.

Notes
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This PR also resolves BHV-3339.
This PR is dependent on an Enyo PR: https://github.com/enyojs/enyo/pull/696

Enyo-DCO-1.1-Signed-off-by: Aaron Tam <aaron.tam@lge.com>