Merge topic 'unity-build-per-config'

129e3c6540 Unity Build: Fix per-config sources in multi-config generators
ea289314ef VS: Fix pre-VS15.8 unity build exclusion of per-config sources
53990059da cmLocalGenerator: Add dedicated types to hold unity source info
de6e362a88 cmLocalGenerator: Clarify name of method to write unity source include lines
3017b3e7d4 cmLocalGenerator: Simplify unity source copy-if-different logic
0b56f92576 cmLocalGenerator: De-duplicate unity source file generation

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6720