CMAKE: Allow the project_binary_dir to contain a whitespace

[weiznich]

What does this PR do?

This PR fixes an issue where installing from a build directory that contains a whitespace fails due to missing path escaping. It's a trivial fix by just escaping the two relevant places.

What are related issues/pull requests?

I did not fill an issue for that, as it seemed easier to just submit this fix.

Tasklist

• Make sure code is correctly formatted (cf pre-commit configuration)
• Add test case(s)
• Add documentation
• Updated Python API documentation (swig/include/python/docs/)
• Review
• Adjust for comments
• All CI builds and checks have passed

Environment

Provide environment details, if relevant:

• OS: Fedora 39
• Compiler: GCC 13.2

[coveralls]

coverage: 68.801% (-0.001%) from 68.802%
when pulling 2a79606 on GiGainfosystems:cmake_fixes
into 51bf340 on OSGeo:master.