Additional validation and escaping for file names.

This adds additional front and backend validations for task order file
names. We are now restricting file names to a whitelist regex of
[A-Za-z0-9\-_ \.] for simplicity.

Note:
On the frontend, the filename string must have at least one character.
This is not true in the backend validation; because of the way the
entire task order form is validated, requiring input would break the
business logic currently implemented.

js/lib/input_validations.js

@@ -104,4 +104,11 @@ export default {
     unmask: ['(', ')', '-', ' '],
     validationError: 'Please enter a 10-digit phone number',
   },
+  restrictedFileName: {
+    mask: false,
+    match: /^[A-Za-z0-9\-_ \.]+$/,
+    unmask: [],
+    validationError:
+      'File names can only contain the characters A-Z, 0-9, space, hyphen, underscore, and period.',
+  },
 }