ENH: Add minimal functionality

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/381. Review is done in https://gitlab.com/caosdb/caosdb-julialib/-/merge_requests/2

Insert a meaningful description for this merge request here.  What is the
new/changed behavior? Which bug has been fixed? Are there related Issues?

Focus

Point the reviewer to the core of the code change. Where should they start
reading? What should they focus on (e.g. security, performance,
maintainability, user-friendliness, compliance with the specs, finding more
corner cases, concrete questions)?

Test Environment

How to set up a test environment for manual testing?

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.

src/CaosDB.jl

@@ -34,12 +34,17 @@ export evaluate_return_code, CaosDBException
 
 using CaosDB
 
+"""
+The parent type of all CaosDB errors that can also be used for testing.
+"""
+abstract type CaosDBException <: Exception end
+
 """
 A generic exception that will be raised in case of non-zero return
 values of the calls to libccaosdb. May carry a message string and a
 code.
 """
-struct CaosDBException <: Exception
+struct GenericCaosDBException <: CaosDBException
     msg::String
     code::Cint
 end
@@ -50,7 +55,7 @@ Base.showerror(io::IO, e::CaosDBException) = print(io, "CaosDBException: ", e.ms
     function evaluate_return_code(code::Cint)
 
 Evaluate the return code of a libccaosdb ccall and raise a
-`CaosDBException` in case of a non-zero return code.
+`GenericCaosDBException` in case of a non-zero return code.
 """
 function evaluate_return_code(code::Cint)
     if code != 0
@@ -60,7 +65,7 @@ function evaluate_return_code(code::Cint)
             (Cint,),
             code
         )
-        throw(CaosDBException(unsafe_string(msg), code))
+        throw(GenericCaosDBException(unsafe_string(msg), code))
     end
 end