Allow specifying a default target for debugging tests

[Nerixyz]

When debugging tests, having the quick picker open up repeatedly is annoying. I'd like to specify a default target that gets used when debugging tests.
I've implemented an MVP in Nerixyz@2fb1e85. You set cmake.ctest.testSuiteDelimiter.debugLaunchTarget to the target name (seems like that's the only decent identifier) and if the target exists, it will be used - otherwise the picker is shown. I noticed

vscode-cmake-tools/src/ctest.ts

Line 933 in ed6d9ad

// TODO: we can remember the last choice once the CMake side panel work is done

... but I don't know about the status of that, and this would require choosing the target once for every session. Does my MVP go in the right direction to open a PR? (the wording might be a bit confusing as CMake also has "targets", but that doesn't impact the functionality)