[upd] Add a global GraphView

Context

A recurring issue in Aidge is the broad use of the name attribute for Nodes.

Currently, names are optional, but this very fact leads to many error:

• overlapping names
• absence of default naming convention using counters
• some nodes are not accessible because they have no names

This issue proposes several solutions:

• Creation of a global GraphView that would store every node. Hence, changing a Node's name would not get the risk of overlapping with another one.
• The global graph could be used to store a counter of each Operator type, it would be used for default naming. For example: Conv_4

This feature could also be merged with a check when a name is set that it is not of the form \D+_\d+

• A default name when created would allow to match any Node in any graph