fix(format): generate correct index links for Azure DevOps

[princjef]

Unlike GitHub, Azure DevOps does not strip unprinted text from headers when generating the link to them. As a result, the addition of code links to the headers broke the Azure DevOps index links.

This change makes link generation more robust and changes the index link inputs to match the actual header values. This necessitated some changes:

• The GitHub format's LocalHref() now strips any non-printable text before generating the link contents. This allows more complicated header contents (such as those with links inside of them) to produce the correct output, rather than having to know the plain text form of the header in advance.
• The Azure DevOps link format is considerably harder to get right. The previous backslash escaping approach doesn't work when the link text itself contains a link (the DevOps link generator bails completely). A more robust solution turned out to be URL-escaping the entire link contents, which DevOps is able to handle regardless of contents.

[princjef]

The linter wasn't picking up on the fact that the templates.go file is autogenerated, so updated the script to move the comment to the top of the file.