Memoize node specific information

[pgiraud]

Is your feature request related to a problem? Please describe.

The Memoize node type was added in PG14 and adds its own information.
https://www.depesz.com/2025/08/04/waiting-for-postgresql-19-display-memoize-planner-estimates-in-explain/

There is:

• Hits added in PG14,
• Estimates expected in PG19.

Describe the solution you'd like

The Hits part is not parsed correctly for now.
The Estimates should be left aside until PG19 is out.

It's important to see

Additional context
https://explain.dalibo.com/plan/e6ghgcba7921d280#plan/node/3 <- plan in text format

https://explain.dalibo.com/plan/c27bf9hbb3e6c19h#plan/node/3 <- plan in json format