Schema unit tests fail if run outside build directory.

[davidlion]

Bug

If the unit tests are run outside the build directory, e.g.:
./build/unitTest instead of cd build && ./unitTest
you will get 11 failures related to missing schema files.

This is caused by relative paths being used in the schema unit tests.

An error example:

/home/lion/yscope/clp-ffi-go/cpp/clp/components/core/tests/test-Grep.cpp:21: FAILED:
due to unexpected exception with message:
ReaderInterface operation failed

[2023-05-20 23:25:59.016] [info] [test-ParserWithUserSchema.cpp:72] File not found: /home/lion/yscope/clp-ffi-go/cpp/clp/components/tests/test_schema_files/missing_schema.txt

CLP version

460d377

Environment

ghcr.io/y-scope/clp/clp-core-dependencies-x86-ubuntu-focal:main

Reproduction steps

1. build the latest CLP
2. run unitTest outside of your build directory (i.e. run unitTest from any directory other than the file's parent)