Add API Error Handler (#74)

* Add error handler that converts from rpc.Status errors to Watchtower API errors.

* Better testing for ErrorHandler.

* Rename testcase and remove empty default switch case.

* Change the error status back to int64.

* Converting everything to int32s.

jsonpb wraps int64s as a string which we dont like.  We'll figure out how to use values larger than int64s when it comes up.

* Remove special casing for TraceId which isn't needed anymore.

* Removing wrappers from error details since we never need to know when they are set or unset from the end user.

* Using the helper error functions inside the project service.

* Correct usage of hclog, replace panic with Error log.

* Adding periods to all API returned errors, correct spelling, fix missed invalid argument error not using helper function.

* Change our logged errors to Error instead of Warn.

* Add TODO for defining and using our own defined API error codes.

* Add TODO to remove internal error messages.

api/internal/genapi/parse.go

@@ -222,9 +222,7 @@ func parsePBs() {
 				}
 
 			TAGMODIFY:
-				// TraceId needs to be handled differently because it's a
-				// specific value used by OpenTelemetry
-				st.Fields.List[i].Tag.Value = "`" + strings.Replace(regex.FindString(st.Fields.List[i].Tag.Value), "trace_id", "TraceId", 1) + "`"
+				st.Fields.List[i].Tag.Value = "`" + regex.FindString(st.Fields.List[i].Tag.Value) + "`"
 			}
 		}), inAst)