improve cache hash performance

* do not concatenate with timestamp as this is slow, since $file_contents may be big
* use file contents not file path for cache hash only to ensure it works if file_path not set but file_content is
* improves performance by ~5%

src/Psalm/Internal/Provider/ClassLikeStorageCacheProvider.php

@@ -112,7 +112,7 @@ public function getLatestFromCache(
 
     private function getCacheHash(?string $file_path, ?string $file_contents): string
     {
-        $data = ($file_path ? $file_contents : '') . $this->modified_timestamps;
+        $data = $file_contents ? $file_contents : $this->modified_timestamps;
         return PHP_VERSION_ID >= 80100 ? hash('xxh128', $data) : hash('md4', $data);
     }
 

src/Psalm/Internal/Provider/FileStorageCacheProvider.php

@@ -119,7 +119,10 @@ public function removeCacheForFile(string $file_path): void
 
     private function getCacheHash(string $file_path, string $file_contents): string
     {
-        $data = ($file_path ? $file_contents : '') . $this->modified_timestamps;
+        // do not concatenate, as $file_contents can be big and performance will be bad
+        // the timestamp is only needed if we don't have file contents
+        // as same contents should give same results, independent of when file was modified
+        $data = $file_contents ? $file_contents : $this->modified_timestamps;
         return PHP_VERSION_ID >= 80100 ? hash('xxh128', $data) : hash('md4', $data);
     }