ENH: Support FIND and COUNT queries

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/399. Introduces FIND and Count queries.

Focus

Most changes are in transaction.h and transaction.cpp.

Test Environment

Unit and integration tests with server in f-grpc-f-query

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• All automated tests pass
• Reference related Issues
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  • Intent of new code
  • Problems with old code
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Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• [ ] Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
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src/caosdb/transaction.cpp

@@ -161,8 +161,6 @@ auto Transaction::RetrieveById(const std::string &id) noexcept -> StatusCode {
   return this->status.GetCode();
 }
 
-// TODO(fspreck) What about count queries (mixed with retrievals),
-// what about unique queries?
 auto Transaction::Query(const std::string &query) noexcept -> StatusCode {
   ASSERT_CAN_ADD_QUERY
 
@@ -182,7 +180,7 @@ auto Transaction::DeleteById(const std::string &id) noexcept -> StatusCode {
   auto *sub_request = this->request->add_requests();
   sub_request->mutable_delete_request()->set_id(id);
 
-  this->status = TransactionStatus::READY();
+  this->status = TransactionStatus::GO_ON();
   return this->status.GetCode();
 }