Add in error type to rpc spans #2812

[thompson-tomo]

Fixes #2812

Changes

The rpc spans now contains the error.type attribute for capturing that detail.

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[thompson-tomo]

Waiting on #2738 to progress this PR

[KalleOlaviNiemitalo]

For JSON-RPC, Microsoft defines an error.data object schema that can name an exception type as well as the types of inner exceptions that caused the exception. See Throwing and handling exceptions and CommonErrorData.TypeName.

Taking such a type name from the error object and using it as error.type in telemetry risks blowing the cardinality too high; but if the client and the server are part of the same product, so that the client can trust the server to keep the cardinality low, then I think it's OK.

[thompson-tomo]

So for jsonrpc spans error.type would likely be sourced from the error.code property hence providing low cardinality.