tag: add namespace rules for redirect tags

[NovemLinguae]

Fixes #1459 Fix redirect category namespace detection

I found 184 {{R to/from X}} style redirect tags that are namespace-specific. This PR codes Twinkle to not display these unless it is the correct namespace.

I copy/pasted a utility function from Stack Overflow, and used a comment with a URL as attribution.

Here's a couple test cases to check:

			var insideMainspaceOnly = [
				'R from acronym',
			];
			var insideTalkNamespaceOnly = [
				'R from remote talk page'
			];
			var disambiguationPagesOnly = [
				'R to disambiguation page'
			];
			var outsideUserspaceOnly = [
				'R to user namespace'
			];

[NovemLinguae]

@siddharthvp Is this patch OK to merge despite not agreeing with the 2 code review comments? Are your concerns sufficiently addressed?

[NovemLinguae]

@siddharthvp After I fix the merge conflict, is this patch OK to merge despite not agreeing with the 2 code review comments? Are your concerns sufficiently addressed?

[siddharthvp]

@NovemLinguae Yeah go ahead. Sorry about the delayed response. Didn't realise this has been sitting for more than a year. How time flies.