Fix LENGTH function name across databases

Signed-off-by: Côme Chilliet <come.chilliet@nextcloud.com>

lib/private/DB/QueryBuilder/FunctionBuilder/FunctionBuilder.php

 	public function charLength($field, $alias = ''): IQueryFunction {
 		$alias = $alias ? (' AS ' . $this->helper->quoteColumnName($alias)) : '';
 		$quotedName = $this->helper->quoteColumnName($field);
-		return new QueryFunction('LENGTH(' . $quotedName . ')' . $alias);
+		return new QueryFunction('CHAR_LENGTH(' . $quotedName . ')' . $alias);
 	}
 
 	public function max($field): IQueryFunction {

lib/private/DB/QueryBuilder/FunctionBuilder/OCIFunctionBuilder.php

 		$quotedName = $this->helper->quoteColumnName($field);
 		return new QueryFunction('LENGTHB(' . $quotedName . ')' . $alias);
 	}
+
+	public function charLength($field, $alias = ''): IQueryFunction {
+		$alias = $alias ? (' AS ' . $this->helper->quoteColumnName($alias)) : '';
+		$quotedName = $this->helper->quoteColumnName($field);
+		return new QueryFunction('LENGTH(' . $quotedName . ')' . $alias);
+	}
 }

lib/private/DB/QueryBuilder/FunctionBuilder/SqliteFunctionBuilder.php

 		$quotedName = $this->helper->quoteColumnName($field);
 		return new QueryFunction('LENGTH(CAST(' . $quotedName . ' as BLOB))' . $alias);
 	}
+
+	public function charLength($field, $alias = ''): IQueryFunction {
+		$alias = $alias ? (' AS ' . $this->helper->quoteColumnName($alias)) : '';
+		$quotedName = $this->helper->quoteColumnName($field);
+		return new QueryFunction('LENGTH(' . $quotedName . ')' . $alias);
+	}
 }