Add to table search path... either point solution or general

[skliper]

Is your feature request related to a problem? Please describe.
Power users have had to clone and own the cmake logic for adding tables to implement preferred directory structure and naming patterns in searching for the table files. Currently not a good way (that I know of) to customize:

cFE/cmake/arch_build.cmake

Lines 128 to 140 in a47abba

	if (EXISTS "${MISSION_DEFS}/tables/${TGT}_${TBLWE}.c")
	set(TBL_SRC "${MISSION_DEFS}/tables/${TGT}_${TBLWE}.c")
	elseif (EXISTS "${MISSION_SOURCE_DIR}/tables/${TGT}_${TBLWE}.c")
	set(TBL_SRC "${MISSION_SOURCE_DIR}/tables/${TGT}_${TBLWE}.c")
	elseif (EXISTS "${MISSION_DEFS}/tables/${TBLWE}.c")
	set(TBL_SRC "${MISSION_DEFS}/tables/${TBLWE}.c")
	elseif (EXISTS "${MISSION_SOURCE_DIR}/tables/${TBLWE}.c")
	set(TBL_SRC "${MISSION_SOURCE_DIR}/tables/${TBLWE}.c")
	elseif (IS_ABSOLUTE "${TBL}")
	set(TBL_SRC "${TBL}")
	else()
	set(TBL_SRC "${CMAKE_CURRENT_SOURCE_DIR}/${TBL}")
	endif()

Describe the solution you'd like
Some way to customize the search path... or we could just do a point solution where we add the desired search path for this stakeholder.

if (EXISTS "${MISSION_DEFS}/${TGT}/tables/${TBLWE}.c")

Describe alternatives you've considered
None

Additional context
None

Requester Info
Jacob Hageman - NASA/GSFC