Fix CUTLASS local work driver setup

[DCM-Uni-Paderborn]

This PR fixes two small setup issues encountered when building and selecting the CUTLASS local work driver from downstream projects such as CP2K.

Changes

• Use direct CMake boolean checks for fetched ExchCXX and IntegratorXX package discovery.
• Propagate CMAKE_POSITION_INDEPENDENT_CODE to fetched ExchCXX and IntegratorXX targets when they are built as GauXC subprojects.
• Normalize local work driver names by trimming whitespace and uppercasing via unsigned-character-safe std::toupper handling.

Motivation

The PIC propagation avoids relocation/link issues when GauXC is built as part of a shared downstream library with fetched static dependencies. The local work driver normalization makes inputs such as Scheme1-CUTLASS robust against surrounding whitespace and avoids undefined behavior from passing signed chars directly to std::toupper.

Validation

• git diff --check: OK
• Line-length check on touched files: OK
• cmake -S . -B /tmp/gauxc-cutlass-build-fixes-configure -DGAUXC_ENABLE_MPI=OFF -DGAUXC_ENABLE_OPENMP=OFF -DGAUXC_ENABLE_TESTS=OFF -DGAUXC_ENABLE_HDF5=OFF -DGAUXC_ENABLE_ONEDFT=OFF -DCMAKE_POSITION_INDEPENDENT_CODE=ON: OK
• cmake --build /tmp/gauxc-cutlass-build-fixes-configure -j 4: OK