Feature Request: Micrometer Metrics for templates

[checketts]

I would like to investigate adding some metrics to Thymeleaf. The Spring library already uses Micrometer so this won't introduce a new dependency.

I'm primarily interested in recording which templates are being used. Would a PR for that be welcome? Another metric would be to record when there are template errors.

Proposed metric names would be:

Counter: thymeleaf.template.used (tags: templateName), I'm hoping to record usage via views, fragments, and layout, perhaps include that as a tag.
Counter: thymeleaf.template.errors (tags: templateName, is possible)

[checketts]

Any concerns around this idea? Perhaps I should just do a spike in my own codebase to see how I might do it without requiring a Thymeleaf change... (Though I would be happy to contribute the idea upstream)