Rollup merge of rust-lang#80543 - LeSeulArtichaut:notify-close, r=spastorino

Notify when an `I-prioritize` issue is closed or reopened

Companion PR to rust-lang/triagebot#1078, blocked on that PR.
r? `@spastorino` cc `@rust-lang/wg-prioritization`

Author: Manishearth

triagebot.toml

@@ -102,6 +102,8 @@ message_on_add = """\
 - Needs `I-nominated`?
 """
 message_on_remove = "Issue #{number}'s prioritization request has been removed."
+message_on_close = "Issue #{number} has been closed while requested for prioritization."
+message_on_reopen = "Issue #{number} has been reopened."
 
 [notify-zulip."T-rustdoc"]
 required_labels = ["I-nominated"]