x/tools/gopls: add telemetry for whether people use rename, extract, inline, change signature

[madelinekalil]

We want to understand how often people use these tools, and how often they produce errors. Also, can we add information about the type of the object that the tool is called on?

[adonovan]

We want to understand how often people use these tools, and how often they produce errors. Also, can we add information about the type of the object that the tool is called on?

We can certainly add counters for UI actions such as initiating a refactoring.

It's also feasible to measure their failure rate, or the type of the renamed symbol, but I wonder what we would gain from both of those kinds of information. Failures arise from a huge variety of causes, some of which are the tool correctly doing its job (e.g. pointing out that the requested is inappropriate for some reason). And renaming must support all kinds of symbol, even if we expect that the vast majority of renamings are on variables, functions, and types (probably in that order).

[madelinekalil]

Good point, I'll start by implementing counters just for the use of these tools without measuring failure.