Tighten parameter substitution tolerance

In collection templating syntax, do not tolerate whitespace after dollar sign. So while `{{ $param }}` is valid `{{ $ param }}` will be ignored.

src/application/Parser/Script/Compiler/Expressions/SyntaxParsers/ParameterSubstitutionParser.ts

@@ -1,7 +1,7 @@
 import { RegexParser, IPrimitiveExpression } from '../Parser/RegexParser';
 
 export class ParameterSubstitutionParser extends RegexParser {
-    protected readonly regex = /{{\s*\$\s*([^}| ]+)\s*}}/g;
+    protected readonly regex = /{{\s*\$([^}| ]+)\s*}}/g;
     protected buildExpression(match: RegExpMatchArray): IPrimitiveExpression {
         const parameterName = match[1];
         return {

tests/unit/application/Parser/Script/Compiler/Expressions/SyntaxParsers/ParameterSubstitutionParser.spec.ts

@@ -23,6 +23,11 @@ describe('ParameterSubstitutionParser', () => {
                 code: 'He{{$firstParameter}}!!',
                 expected: [new ExpressionPosition(2, 21) ],
             },
+            {
+                name: 'does not tolerate space after dollar sign',
+                code: 'He{{ $ firstParameter }}!!',
+                expected: [ ],
+            },
         ];
         for (const testCase of testCases) {
             it(testCase.name, () => {