Improvement: Make "Last Active" available in neonctl branches list

[ruf-io]

From Discord: https://discord.com/channels/1176467419317940276/1281248863470096446/1281248863470096446

Is there a way to get the Last active field from the browser UI with this command: neonctl branches list --project-id PROJECT_ID --output json? Currently, I only see a created_at and an updated_at, neither of which match the data of the Last active column. We're trying to automate branch cleanup and need this data to know which branches are safe to be pruned.

So essentially, we need the same information that powers the "Last Active" column in the Neon Console UI made available in the neonctl response to neonctl branches list