telemetry: Only send requests if data has changed

[radeksimko]

Depends on hashicorp/terraform-schema#89
Depends on #761

According to manual testing with a single installed module from https://registry.terraform.io/modules/terraform-aws-modules/eks/aws/latest this can reduce the amount of telemetry requests to about half (from 32 to 14).

There's probably more we can do here - e.g. avoid sending telemetry for unsaved data. This is not only extra overhead, but also pollutes the data with "unfinished" provider or backend names. However this would require more effort - probably queueing the telemetry data somewhere and then adding a hook which gets triggered by textDocument/didSave. Either way not something I wanted to tackle in this PR.

[dbanck]

Implementation LGTM! 🌟

I wondered if we prefer to send a "full" properties body when something changes or just the change? For example, we're sending providerRequirements and tfVersion in the current implementation, even if just tfRequirements has changed.

[radeksimko]

I wondered if we prefer to send a "full" properties body when something changes or just the change? For example, we're sending providerRequirements and tfVersion in the current implementation, even if just tfRequirements has changed.

Yes, this is on purpose, because it makes querying the data in Kusto easier (more accurate) if we're querying against complete records.

[github-actions]

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