Add CMake style checker (parflow#733)

Add style checker gersemi for CMake files, will be part of the style check CI test.

Author: smithsg84

CMakeLists.txt

@@ -215,9 +215,9 @@ error prone.
 
 ParFlow uses automated code formatters to check code as one of the
 checks in our CI system.  Incorrectly formatted code will fail the
-check and won't be merged.  The check is done using Uncrustify for C
-and Black for Python.  A script is provided to automatically reformat 
-code and do the check.
+check and won't be merged.  The check is done using Uncrustify for
+C/C++, Black for Python and gersemi for CMake.  A script is provided
+to automatically reformat code and do the check.
 
 To check if the coding style is correct run the pfformat script at the 
 root of the PF source tree:
@@ -234,19 +234,17 @@ cd parflow
 ./bin/pfformat
 ```
 
-You must have installed **Uncrustify version 0.79.0** in order for this to
-work.  For Python, ParFlow uses the **Black code formatter pinned to
-version 26.3.1**.  Black is installed into the ParFlow Python
-environment during installation, so you normally don't need to install
-it manually, but if you do you should ensure that you are using
-**Black 26.3.1** to match the version used in CI.
+The pfformat command uses an installed Python environment and 
+should get the correct versions of the formatting tools.
 
 Information and source on these tools can be found here:
 
 [Uncrustify](https://github.com/uncrustify/uncrustify)
 
 [Black](https://github.com/psf/black)
 
+[gersemi](https://github.com/BlankSpruce/gersemi)
+
 ### Why auto code formatting?
 
 Enforcing a common code indentation and other style format is fairly

CONTRIBUTING.md

@@ -128,7 +128,7 @@ function main() {
    do
       if $check
       then
-	 if output=$(uncrustify --check -c bin/parflow.cfg $i)
+	 if output=$(uncrustify --check -c bin/parflow.cfg $i 2>&1)
 	 then
 	    log 'pfformat PASSED %s\n' $i
 	 else
@@ -140,10 +140,9 @@ function main() {
       fi
    done
 
-   # Disable this for now while Python is being refactored.
    if $check
    then
-      if output=$($PARFLOW_DIR/bin/pfpython -m black . --check)
+      if output=$($PARFLOW_DIR/bin/pfpython -m black . --check 2>&1)
       then
 	 log 'pfformat PASSED %s\n' $i
       else
@@ -154,6 +153,19 @@ function main() {
       $PARFLOW_DIR/bin/pfpython -m black .
    fi
 
+   if $check
+   then
+      if output=$($PARFLOW_DIR/bin/pfpython -m gersemi . --check 2>&1)
+      then
+	 log 'pfformat PASSED %s\n' $i
+      else
+	 printf 'pfFormat FAILED\nCMake style checker gersemi output was «%s»\n' "$output\n"
+	 failed=true
+      fi
+   else
+      $PARFLOW_DIR/bin/pfpython -m gersemi --in-place .
+   fi
+
    if $check
    then
       if $failed ;