Fix pickle and deepcopy of graph types

[robsdedude]

Since the types of Relationships are tied to the Graph object they belong to, fixing pickle support for graph types means that Relationships with the same name will have a different type after deepcopying or pickling and unpickling them or their graph.

Example

Before the fix

import copy
import pickle

import neo4j
import neo4j.graph


g1: neo4j.graph.Graph = some_graph()
g2 = copy.deepcopy(g1)
# g2 = pickle.loads(pickle.dumps(g1))  # errors out

# assuming the graph contained relationships of the type KNOWS
cls_knows1: type[neo4j.graph.Relationship] = g1.relationship_type("KNOWS")
cls_knows2: type[neo4j.graph.Relationship] = g2.relationship_type("KNOWS")
# the types are the same even after the deepcopy
assert cls_knows1 is cls_knows2

# assuming the graph did not contain relationships of the type NEW
cls_new1: type[neo4j.graph.Relationship] = g1.relationship_type("NEW")
cls_new2: type[neo4j.graph.Relationship] = g2.relationship_type("NEW")
# each graph created their own type/class
assert cls_new1 is not cls_new2

After the fix:

g1: neo4j.graph.Graph = some_graph)
g2 = copy.deepcopy(g1)
# or (works now):
# g2 = pickle.loads(pickle.dumps(g1))

# assuming the graph contained relationships of the type KNOWS
cls_knows1: type[neo4j.graph.Relationship] = g1.relationship_type("KNOWS")
cls_knows2: type[neo4j.graph.Relationship] = g2.relationship_type("KNOWS")
# different graphs always track different relationship types/classes
assert cls_knows1 is not cls_knows2

# assuming the graph did not contain relationships of the type NEW
cls_new1: type[neo4j.graph.Relationship] = g1.relationship_type("NEW")
cls_new2: type[neo4j.graph.Relationship] = g2.relationship_type("NEW")
# always different
assert cls_new1 is not cls_new2

Fixes: #1132

[StephenCathcart]

Looks good!

[robsdedude]

Currently waiting for a discussion with the team how to deal with the change in equality of deep copied graph types.