ICU-22740 Add -Wctad-maybe-unsupported to CI jobs that use -Wall -Wex…

…tra.

This modifies the following jobs:

C: Linux Clang-16 WarningsAsErrors (Ubuntu 20.04)
C: macOS(Latest) Clang WarningsAsErrors

.ci-builds/.azure-pipelines-icu4c.yml

@@ -164,7 +164,7 @@ jobs:
  displayName: 'Build only (WarningsAsErrors)'
  env:
  CC: clang-16
- CPPFLAGS: '-Werror -Wno-strict-prototypes -Wall -Wextra -Wextra-semi -Wundef -Wnon-virtual-dtor -Wsuggest-override'
+ CPPFLAGS: '-Werror -Wno-strict-prototypes -Wall -Wextra -Wextra-semi -Wundef -Wnon-virtual-dtor -Wsuggest-override -Wctad-maybe-unsupported'
  CXX: clang++-16
 #-------------------------------------------------------------------------
 - job: ICU4C_Clang16_Cpp20_Ubuntu_2004
@@ -555,7 +555,7 @@ jobs:
  lfs: true
  fetchDepth: 10
  - script: |
- export CPPFLAGS="-Werror -Wall -Wextra -Wextra-semi -Wundef -Wnon-virtual-dtor" && cd icu4c/source && ./runConfigureICU MacOSX && make -j -l2.5 check
+ export CPPFLAGS="-Werror -Wall -Wextra -Wextra-semi -Wundef -Wnon-virtual-dtor -Wctad-maybe-unsupported" && cd icu4c/source && ./runConfigureICU MacOSX && make -j -l2.5 check
  displayName: 'Build and Test (WarningsAsErrors)'
  env:
  CC: clang