fix CTest

[njzjz]

1. set WORKING_DIRECTORY for runUnitTest_cc and runUnitTest_c (help find the graph files);
2. set BUILD_RPATH for deepmd_cc. (help find deepmd_op)

Then CTest should work, using either the ctest or cmake --build . --target test command.

[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (0d5737f) 75.45% compared to head (366ee3a) 75.45%.

Additional details and impacted files

@@           Coverage Diff           @@
##            devel    #2828   +/-   ##
=======================================
  Coverage   75.45%   75.45%           
=======================================
  Files         242      242           
  Lines       24205    24205           
  Branches     1537     1537           
=======================================
  Hits        18265    18265           
  Misses       5023     5023           
  Partials      917      917           

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