Autogen: Add detection of UI file changes to the pre-build VS case

This is achieved by adding a rule file which carries the UI files as dependencies but performs no meaningful command. Its output path points to a timestamp file which is instead touched by the pre-build command that runs autogen. The rule file therefore triggers the build if any of the files have been changed more recently than the last autogen run.

Fixes: #17959
Fixes: #18741
36 jobs for !5999 with vs-autouic-on-ui-file-change in 76 minutes and 26 seconds (queued for 2 seconds)
detached
Status Name Job ID Coverage
  Build
passed build:centos6-x86_64 #5692912
cmake build docker linux manual

00:03:39

passed build:debian10-iwyu #5692909
cmake build docker linux

00:02:16

passed build:fedora33-ninja #5692913
cmake build docker linux linux-3.17 manual

00:02:21

passed build:fedora33-sphinx #5692911
cmake build docker linux linux-3.17

00:05:09

passed build:fedora33-tidy #5692910
cmake build docker linux linux-3.17

00:19:10

manual build:macos-x86_64-makefiles #5692915
cmake macos shell xcode-12.4 nonconcurrent manual
manual build:macos-x86_64-ninja #5692914
cmake macos shell xcode-12.4 nonconcurrent manual
passed build:windows-vs2019-x64-ninja #5692916
cmake windows shell vs2019 msvc-19.28-16.9 nonconcurrent manual

00:09:26

 
  Test
passed test:fedora33-ninja #5692917
cmake docker linux linux-3.17 x11

00:04:31

created test:macos-x86_64-makefiles #5692919
cmake macos shell xcode-12.4 nonconcurrent
created test:macos-x86_64-ninja #5692918
cmake macos shell xcode-12.4 nonconcurrent
passed test:windows-vs2019-x64-ninja #5692920
cmake windows shell vs2019 msvc-19.28-16.9 nonconcurrent

00:13:33

 
  Test Ext
passed test:cuda10.2-nvidia #5692923
cmake cuda-rt docker linux

00:01:50

passed test:debian10-ninja #5692921
cmake build docker linux linux-3.17

00:03:17

passed test:fedora33-makefiles #5692922
cmake build docker linux linux-3.17

00:09:02

passed test:fedora33-ninja-multi #5692924
cmake build docker linux linux-3.17

00:02:55

created test:macos-x86_64-xcode #5692925
cmake macos shell xcode-12.4 concurrent
passed test:windows-vs2019-x64 #5692926
cmake windows shell vs2019 msvc-19.28-16.9 concurrent

00:26:57

 
  External
passed cdash

passed ghostflow-check-master

passed ghostflow-stager

passed cdash

passed cdash

passed cdash

passed cdash

passed cdash

passed cdash

passed cdash

passed cdash

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager

passed ghostflow-stager