policy: Add policy CMP0052

This policy switches between the old EVIS parser and the new, faster
parser.
tests: Add tests for CMP0052
tests: Fix StringFileTest for CMP0052
EVIS: Reimplement using custom parsing code

Testing the configure (no generate) step with ParaView shows ~20%
performance improvement (~47s -> ~39s on my machine).

In terms of complete configure/generate steps, further testing with
ParaView shows a 20% performance improvement over 2.8.12.2 with Unix
Makefiles and minimal with Ninja. Ninja is less because it generate step
is the expensive part (future work will address this) by a long shot and
these changes help the configure step for the most part.
relnotes: Add release notes for the branch
Merge topic 'dev/faster-evis' into next

670f4d6f relnotes: Add release notes for the branch
4ae4128f EVIS: Reimplement using custom parsing code
162a583f tests: Fix StringFileTest for CMP0052
b667320a tests: Add tests for CMP0052
07e466ca policy: Add policy CMP0052