Better Error Handling and Logging

Summary

Better error handling (less exceptions, more error codes) and logging (for more detailed error handling and configuration issues).

Issue: https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/390

See also the tests in caosdb-cppinttest!2 (merged)

Focus

• The TransactionStatus class represents the current status of a Transaction instance.
• The TransactionCode is a numeric representation of the status and intended for c-compatible error handling.
• Messages and Message classes handle the errors, warnings and info messages that come from the server.
• Logging: The logging can be configured via a json file. Otherwise the default configuration is in place.
• A lot of code was moved in order to comply with -pedantic flag. Don't waste your time

Test Environment

Unit tests should run as described in README_SETUP

Integration tests should run against a linkahead in the f-grpc branch

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

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.
• Check: Are there spezifications? Are they satisfied?

For further good practices have a look at our review guidelines.

include/caosdb/transaction_status.h

@@ -48,6 +48,8 @@ using caosdb::exceptions::TransactionError;
  */
 class TransactionStatus {
 public:
+  // REFACTORING NEEDED: When you touch this code again consider writing a
+  // macro, because this is a lot of redundant code here...
   inline static auto INITIAL() -> const TransactionStatus & {
     static const TransactionStatus initial(
       StatusCode::INITIAL, caosdb::get_status_description(StatusCode::INITIAL));
@@ -66,6 +68,9 @@ public:
   }
   inline static auto RPC_ERROR(const std::string &details)
     -> const TransactionStatus {
+    // We use the GENERIC_RPC_ERROR here because we might want to add further
+    // RPC_ERROR states with different error codes (which stem from GRPC) here
+    // in the future.
     return TransactionStatus(
       StatusCode::GENERIC_RPC_ERROR,
       caosdb::get_status_description(StatusCode::GENERIC_RPC_ERROR) +