dedent function and tagged template function

[harrysolovay]

Is your feature request related to a problem? Please describe.

A dedent function is a common need when working with tagged template strings, as they enhance the legibility of strings relative to other code (without which indentations become chaotic).

Describe the solution you'd like

A dedent.ts function in the text directory. This file can export an overloaded version of dedent such that it works with both string arguments and template strings arrays + quasis.

Describe alternatives you've considered

While there are other libraries for this, I'd prefer only to use the Deno Standard Library wherever possible. This seems like a good candidate for Deno Standard.

[kt3k]

npm:dedent has 27M weekly downloads https://www.npmjs.com/package/dedent

A similar feature is proposed as a language feature (String.dedent) https://github.com/tc39/proposal-string-dedent

I think this is probably a sensible addition to std/text.