feat(chips): allow mdChips component to be used with 'data-'-prefixes

[janeisklar]

Compare to pull request #7056 for a similar issue with md-menu
Changes:

• <md-chips>, <md-chip-template>, etc. can now also be used as <data-md-chips>, <data-md-chip-template>
• added a basic usage demo that features those <data-*> tags
• made the corresponding tests parametrized so that they are executed both with and without the data-prefix

Background:
'data-'-prefixing is f.e. done by angular-htmlify and allows for the W3C validation of angular templates

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[janeisklar]

I signed it!

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[devversion]

I don't like that. This would require a selector for x- as well.

We should either apply a class, to identify the chips directive.

[ThomasBurleson]

A generic solution to data- prefixing is in progress. Will not merge this PR.

[janeisklar]

Is there an issue that you could reference allowing us to track the progress of the mentioned generic solution?

[devversion]

@janeisklar Yes it is.

• Issue: refactor: utils should have a function to get all prefixed attributes #8121
• PR: feat(prefixer): add service to prefix attributes #8163