MATLAB switch statement support (#634)

## MATLAB switch statement support
This PR adds Tree-sitter coverage of MATLAB switch statements. CI tests
are also included.

``` matlab
switch x
    case 1
        n = 1;
        j = 1;
    case {3, three, 'three'}
        n = 3;
    case {{1, 2, 3,}, {7, 8, 9}}
        n = 6;
    otherwise
        n = 0;
end
```

## Relevant features
- Switch statements are translated into CAST conditional logic
- Multiple argument cases are reduced to single list inclusion test
- Case arguments may be of differing datatypes (string, number,
identifier)

## Related issues

- Resolves issue #561

---------

Co-authored-by: Joseph Astier <jastier@arizona.edu>

skema/program_analysis/CAST/matlab/cast_out

@@ -2,25 +2,55 @@
 import json
 import sys
 from skema.program_analysis.CAST.matlab.matlab_to_cast import MatlabToCast
+from typing import List
+
+# Show a CAST object as pretty printed JSON with keys filtered for clarity.
+
+# Keys to remove from the output
+#KEY_FILTER = ["source_refs", "default_value", "interpreter"]
+KEY_FILTER = ["source_refs"]
+
+def remove_keys(json_obj, target_keys: List):
+    """ remove all instances of the target keys from the json object"""
+
+    def remove_key(json_obj, target_key):
+        """ remove all instances of the target key from the json object"""
+        if isinstance(json_obj, dict):
+            for target_key in target_keys:
+                if target_key in json_obj.keys():
+                    json_obj.pop(target_key)
+                for key in json_obj.keys():
+                    remove_key(json_obj[key], target_keys)
+        elif isinstance(json_obj, list):
+            for item in json_obj:
+                remove_key(item, target_keys)
+        return(json_obj)
+
+    print(f"Removed keys: {target_keys}")
+    return remove_key(json_obj, target_keys)
+
+
+def show_cast(filename):
+    """ Run a file of any type through the Tree-sitter MATLAB parser"""
+    parser = MatlabToCast(filename)
+    print("\nINPUT FILE:")
+    print(parser.filename)
+    print("\nSOURCE:")
+    print(parser.source)
+    print('\nCAST:')
+    cast_list = parser.out_cast
+    for cast in cast_list:
+        json_obj = cast.to_json_object()
+        # declutter JSON by filtering keys
+        json_obj = remove_keys(json_obj, KEY_FILTER)
+        # pretty print JSON to string
+        output = json.dumps(json_obj, sort_keys=True, indent=2)
+        print(output)
 
-""" Run a file of any type through the Tree-sitter MATLAB parser"""
 
 if __name__ == "__main__":
     if len(sys.argv) > 1:
         for i in range(1, len(sys.argv)):
-            parser = MatlabToCast(sys.argv[i])
-            print("\n\nINPUT:")
-            print(parser.filename)
-            print("\nSOURCE:")
-            print(parser.source)
-            print('\nCAST:')
-            cast_list = parser.out_cast
-            for cast_index in range(0, len(cast_list)):
-                jd = json.dumps(
-                    cast_list[cast_index].to_json_object(),
-                    sort_keys=True,
-                    indent=2,
-                )
-                print(jd)
+            show_cast(sys.argv[i])
     else:
         print("Please enter one filename to parse")