cmake: match filename suffixes with file content

To:
- simplify recognizing CMake sources.
- ensure syntax highlighters use the correct file type.
- sync .h template filename with its autotools counterpart.

Also:
- cmakelint.sh: simplify, alpha sort the filelist.
- perlcheck.sh: simplify.

Closes #20039

scripts/cmakelint.sh

@@ -45,15 +45,13 @@ cd "$(dirname "$0")"/..
 
 {
   if [ -n "${1:-}" ]; then
-    for A in "$@"; do printf "%s\n" "$A"; done
+    for A in "$@"; do printf '%s\n' "$A"; done
   elif git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
-    git ls-files
+    git ls-files '**CMakeLists.txt' '*.cmake'
   else
-    # strip off the leading ./ to make the grep regexes work properly
-    find . -type f | sed 's@^\./@@'
+    find . -type f \( -name 'CMakeLists.txt' -o -name '*.cmake' \)
   fi
-} | grep -E '(^CMake|/CMake|\.cmake$|\.cmake\.in$)' | grep -v -E '(\.h\.cmake|\.c)$' \
-  | xargs \
+} | sort | xargs \
   cmake-lint \
     --suppress-decorations \
     --disable \

scripts/perlcheck.sh

@@ -38,14 +38,11 @@ echo "parallel: ${procs}"
 
 {
   if [ -n "${1:-}" ]; then
-    for A in "$@"; do printf "%s\n" "$A"; done
+    for A in "$@"; do printf '%s\n' "$A"; done
   elif git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
-    {
-      git ls-files | grep -E '\.(pl|pm)$'
-      git grep -l '^#!/usr/bin/env perl'
-    } | sort -u
+    git ls-files '*.pl' '*.pm'
+    git grep -l '^#!/usr/bin/env perl'
   else
-    # strip off the leading ./ to make the grep regexes work properly
-    find . -type f \( -name '*.pl' -o -name '*.pm' \) | sed 's@^\./@@'
+    find . -type f \( -name '*.pl' -o -name '*.pm' \)
   fi
-} | xargs -n 1 -P "${procs}" perl -c -Itests --
+} | sort -u | xargs -n 1 -P "${procs}" perl -c -Itests --