Extra leading spaces seem to affect the parsing of boolean conditions

[As I noted under a different issue](https://github.com/inkle/ink/issues/911#issuecomment-2444160887), having leading spaces in a line could affect the parsing of boolean conditions inside curly brackets. Here's a simple test that demonstrates this issue:
```
[Test()]
public void TestLineBreakAfterChoiceLabel()
{
Story story1 = CompileString(@"
* (label)
{true} choice text
");
Story story2 = CompileString(@"
* (label)
{true} choice text
");
story1.Continue();
String result1 = story1.currentChoices[0].text; // "choice text"
story2.Continue();
String result2 = story2.currentChoices[0].text; // "true choice text"
}
```