storage: update IStorage#file_put_contents docs to match usage

The current phpdoc of IStorage#file_put_contents doesnt corresponds to
it's actual usage in code, e.g.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>

lib/private/Files/ObjectStore/ObjectStoreStorage.php

@@ -439,9 +439,9 @@ class ObjectStoreStorage extends \OC\Files\Storage\Common {
 
 	public function file_put_contents($path, $data) {
 		$handle = $this->fopen($path, 'w+');
-		fwrite($handle, $data);
+		$result = fwrite($handle, $data);
 		fclose($handle);
-		return true;
+		return $result;
 	}
 
 	public function writeStream(string $path, $stream, int $size = null): int {

lib/private/Files/Storage/DAV.php

@@ -486,8 +486,8 @@ class DAV extends Common {
 
 	/**
 	 * @param string $path
-	 * @param string $data
-	 * @return int
+	 * @param mixed $data
+	 * @return int|false
 	 */
 	public function file_put_contents($path, $data) {
 		$path = $this->cleanPath($path);

lib/private/Files/Storage/Flysystem.php

@@ -73,7 +73,11 @@ abstract class Flysystem extends Common {
 	 * {@inheritdoc}
 	 */
 	public function file_put_contents($path, $data) {
-		return $this->flysystem->put($this->buildPath($path), $data);
+		$result = $this->flysystem->put($this->buildPath($path), $data);
+		if ($result === true) {
+			return strlen($data);
+		}
+		return $result;
 	}
 
 	/**

lib/private/Files/Storage/Wrapper/Encoding.php

@@ -309,8 +309,8 @@ class Encoding extends Wrapper {
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 */
 	public function file_put_contents($path, $data) {
 		return $this->storage->file_put_contents($this->findPathToUse($path), $data);

lib/private/Files/Storage/Wrapper/Encryption.php

@@ -234,8 +234,8 @@ class Encryption extends Wrapper {
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 */
 	public function file_put_contents($path, $data) {
 		// file put content will always be translated to a stream write

lib/private/Files/Storage/Wrapper/Jail.php

@@ -259,8 +259,8 @@ class Jail extends Wrapper {
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 */
 	public function file_put_contents($path, $data) {
 		return $this->getWrapperStorage()->file_put_contents($this->getUnjailedPath($path), $data);

lib/private/Files/Storage/Wrapper/Quota.php

@@ -121,8 +121,8 @@ class Quota extends Wrapper {
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 */
 	public function file_put_contents($path, $data) {
 		$free = $this->free_space($path);

lib/private/Files/Storage/Wrapper/Wrapper.php

@@ -250,8 +250,8 @@ class Wrapper implements \OC\Files\Storage\Storage, ILockingStorage, IWriteStrea
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 */
 	public function file_put_contents($path, $data) {
 		return $this->getWrapperStorage()->file_put_contents($path, $data);

lib/public/Files/Storage.php

@@ -230,8 +230,8 @@ interface Storage extends IStorage {
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 * @since 6.0.0
 	 */
 	public function file_put_contents($path, $data);

lib/public/Files/Storage/IStorage.php

@@ -226,8 +226,8 @@ interface IStorage {
 	 * see http://php.net/manual/en/function.file_put_contents.php
 	 *
 	 * @param string $path
-	 * @param string $data
-	 * @return bool
+	 * @param mixed $data
+	 * @return int|false
 	 * @since 9.0.0
 	 */
 	public function file_put_contents($path, $data);