Fix behavior of VersionGroupOptions.exclude

[ecraig12345]

While working on another change, I noticed that the behavior of the VersionGroupOptions.exclude option was basically acting like a second include option: the passed patterns would have to be negated to work. This is very counterintuitive, not useful, and likely was a mistake.

Maybe this diff from one of the tests helps illustrate the before/after behavior. Before, minimatch(packagePath, excludePattern) must return true for one of the exclude patterns, so the exclude pattern had to be negated. After, the option behaves as expected.

  it('should return false if path is excluded with single exclude path', () => {
      // isPathIncluded(packagePath, include, exclude)
-    expect(isPathIncluded('packages/a', 'packages/*', '!packages/a')).toBeFalsy();
+    expect(isPathIncluded('packages/a', 'packages/*', 'packages/a')).toBeFalsy();
  });

This could be a breaking change if anyone was using group.exclude, but given the odd behavior, it seems less likely that anyone was relying on it.

(I also renamed the file the function is located in from utils.ts to isPathIncluded since it only has that one function.)