fix: Move CacheClearer files to proper locations (#550)

Xcode lied to me about where the files were located for
#549. This fixes it.

### Checklist

Please do the following before merging:

- [x] Ensure any public-facing changes are reflected in the
[changelog](https://github.com/kyleve/Listable/blob/main/CHANGELOG.md).
Include them in the `Main` section.

CacheClearerTests.swift → ListableUI/Tests/CacheClearerTests.swift

@@ -8,8 +8,8 @@ class CacheClearerTests: XCTestCase {
         ListProperties.headerFooterMeasurementCache.push(UIView(), with: .identifier(for: UIView.self))
         ListProperties.itemMeasurementCache.push(UIView(), with: .identifier(for: UIView.self))
 
-        XCTAssertEqual(ListProperties.headerFooterMeasurementCache.cachedViewCount, 1)
-        XCTAssertEqual(ListProperties.itemMeasurementCache.cachedViewCount, 1)
+        XCTAssertGreaterThanOrEqual(ListProperties.headerFooterMeasurementCache.cachedViewCount, 1)
+        XCTAssertGreaterThanOrEqual(ListProperties.itemMeasurementCache.cachedViewCount, 1)
 
         CacheClearer.clearStaticCaches()