LibSQL: Partially implement the DELETE command

This implements enough to delete rows filtered by a WHERE clause.

Userland/Libraries/LibSQL/CMakeLists.txt

@@ -1,6 +1,7 @@
 set(SOURCES
     AST/CreateSchema.cpp
     AST/CreateTable.cpp
+    AST/Delete.cpp
     AST/Describe.cpp
     AST/Expression.cpp
     AST/Insert.cpp