cfe_locate_implementation_file doesn't test prefixes that match within entire path

[skliper]

Is your feature request related to a problem? Please describe.
Prefix exclusion dependence on entire path is unexpected, since much of it is out of scope of the defs directory:

cFE/cmake/global_functions.cmake

Lines 57 to 63 in 7f5ebcd

	# A target-specific prefixed filename gets priority over a direct filename match
	# But do not include this variant if the prefix is already part of the basedir
	foreach (PREFIX ${LOCATEIMPL_ARG_PREFIX})
	if (NOT "${BASEDIR}" MATCHES "/${PREFIX}/")
	list(APPEND IMPL_SEARCH_PATH "${BASEDIR}${PREFIX}_${FILE_NAME}")
	endif()
	endforeach()

Describe the solution you'd like
Only match within relative directory

Describe alternatives you've considered
Could just remove the test, an extra check for matching (even if there's already a subdir) shouldn't hurt

Additional context
nasa/cFS#709

Requester Info
Jacob Hageman - NASA/GSFC

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