Extend NxTranslator

[katarinasupe]

The NxTranslator has been changed to inherit from the Translator class, but not all of its parts of code have been adjusted accordingly. For example:

• All exported from the module: https://github.com/memgraph/gqlalchemy/blob/main/gqlalchemy/transformations/translators/nx_translator.py#L161
• Naming (probably better to_cypher_queries_parallel, since nx_to_cypher was changed into to_cypher_queries): https://github.com/memgraph/gqlalchemy/blob/main/gqlalchemy/transformations/translators/nx_translator.py#L174
• Internally, Memgraph saves NetworkX ID as id while for PyG and DGL, it saves them as pyg_id and dgl_id, respectively. It can be changed, but not necessarily.

Besides that, import and export are not following the same set of rules.
Translate from Nx graph to Memgraph rules:

• Values of labels key in Nx graph -> node labels in Memgraph
• Value of TYPE key in Nx graph -> relationship type in Memgraph

Translate from Memgraph graph to Nx graph rules:

• node labels in Memgraph -> Values of label key in Nx graph
• relationship type in Memgraph -> Value of type key in Nx graph