Tidy spacing in templates

[srawlins]

I've been trying to standardize on this style. Two things:

• Indent all HTML and block-like Mustache tags 2 spaces. This style does affect the indentation of the output HTML, but it should not be so many bytes as to matter.
• Write all Mustache tags with an opening space and a closing space, just next to the {/} delimiters. E.g. {{ #getter }} and {{{ linkedGenericParameters }}}. This style does not affect the outputted HTML.

Here I am just touching files that I might need to update for #2021.

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