F async execute

Summary

1. Makes ExecuteAsynchronously actually asynchronous.
2. Version bump of grpc to 1.45.2

Focus

Most of the old execution code has been removed from ExecuteAsynchronously and WaitForIt and has been split up into DoExecuteTransaction(), ProcessCall, ProcessTerminated, and ProcessRetrieveResponse.

ExecuteAsynchronously now only start a background thread running DoExecuteTransaction and WaitForIt joins the background thread until it terminates.

Because we deal with multiple thread now, this MR also needed to introduce a mutex/lock system. We have a special non-public macro for this (TRANSACTION_SYNCRONIZED_BLOCK).

Test Environment

Pipelines should be enough. If we encounter problems in the dependent clients (julia, octave) afterwards we will see what we need to do then.

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doc/CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
+* Transaction::ExecuteAsynchronously is actually asynchronous now.
 * Removed boost from the headers. Boost is only a build dependency from now on.
 
 ### Deprecated