Adds find_package(Catch2) to test_nodes CMakeLists

[tatatupi]

Type of change

• Bug fix
• Documentation/refactoring

Description

In case you have Catch2 installed and the correct system variable for Catch2_DIR, the test_nodes lib won't find the Catch2 package without the explicit directive to see it.
This PR includes find_package(Catch2) to test_nodes CMakeLists.txt to fix that.
And it also adds instructions in README.txt, to create the Catch2_DIR system variable.

Testing

• Qt version tested:
• Existing tests still pass

Breaking changes?

No

Related issue

None.

[tatatupi]

needs more elaboration

[paceholder]

CMakeListst.txt - line 50
add_subdirectory(external) -- there we run the script external/CMakeLists.txt which already searches for catch2.

This is maybe not very clear from the name (external), maybe we should move the fings outside the external directory

[tatatupi]

The problem is that I have Catch2 3.6.0 installed, and the configuration won't work due to the different version. I propose we revert the find_package(Catch2 2.13.7 QUIET) with an explicit version.

And when the system package is found, there should be a find_package(Catch2) inside the test CMakeLists.

Is there a reason you removed the explicit Catch2 version from find_package?