(feat) Add Relation and Tuple operations to Python SWIG bindings

[qequ]

This PR extends the Python SWIG interface to support programmatic access to Relations and Tuples, enabling direct manipulation of Souffle data structures from Python without file I/O.

New Features

SWIGRelation - Access relations by name with metadata queries (arity, size, attribute types/names)
SWIGTuple - Create and read tuples with typed accessors (putString, putInt, putUInt, putFloat and corresponding getters)
SWIGRelationIterator - Iterate over relation tuples with Python's native for loop syntax
Tuple operations - insert(), contains(), purge() for programmatic data manipulation

Example Usage

import SwigInterface

p = SwigInterface.newInstance('myprogram')

# Insert tuples programmatically
edge = p.getRelation('edge')
t = edge.createTuple()
t.putString("A")
t.putString("B")
edge.insert(t)

p.run()

# Iterate over results
for t in p.getRelation('path'):
    print(t.getString(), t.getString())