Add auto-handling of stale PRs/Issues (#7197)

* Add auto-handling of stale PRs/Issues

This adds the configuration for probot-stale, so that PRs and Issues can be automatically pruned without intervention by collaborators.

This marks PRs with `awaiting changes` label after 45 days, and then closes any PR with "Awaiting changes" after 30 days.  Unless they have `awaiting review`, `breaking_changes`, `in progress` or `on hold` labels.

This marks issues as `solved` after 90 days, and then closes them 30 days afterwards. Unless they have `bug`, `discussion, `to do`, `in progress` or `on hold` labels.

* Cleanup the text some

* Update .github/stale.yml

Co-Authored-By: fauxpark <fauxpark@gmail.com>

.github/stale.yml

@@ -0,0 +1,52 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# General configuration
+
+# Pull request specific configuration
+pulls:
+  staleLabel: awaiting changes
+  # Number of days of inactivity before an Issue or Pull Request becomes stale
+  daysUntilStale: 45
+  # Number of days of inactivity before a stale Issue or Pull Request is closed.
+  # Set to false to disable. If disabled, issues still need to be closed manually, but will remain marked as stale.
+  daysUntilClose: 30
+  # Comment to post when marking as stale. Set to `false` to disable
+  markComment: >
+    Thank you for your contribution!
+
+    This pull request has been automatically marked as stale because it has not had
+    activity in the last 45 days. It will be closed in 30 days if no further activity occurs.
+    Please feel free to give a status update now, or re-open when it's ready.
+  # Comment to post when closing a stale Issue or Pull Request.
+  closeComment: >
+    Thank you for your contribution!
+
+    This pull request has been automatically closed because it has not had activity in the last 30 days.
+    Please feel free to give a status update now, ping for review, or re-open when it's ready.
+  # Limit the number of actions per hour, from 1-30. Default is 30
+  limitPerRun: 30
+  exemptLabels:
+    - awaiting review
+    - breaking_change
+    - in progress
+    - on hold
+
+# Issue specific configuration
+issues:
+  staleLabel: solved
+  limitPerRun: 10
+  daysUntilStale: 90
+  daysUntilClose: 30
+  markComment: >
+    This issue has been automatically marked as resolved because it has not had activity in the
+    last 90 days. It will be closed in the next 30 days unless it is tagged properly or other activity
+    occurs.
+  closeComment: >
+    This issue has been automatically closed because it has not had activity in the last 30 days.
+    If this issue is still valid, re-open the issue and let us know.
+  exemptLabels:
+    - bug
+    - in progress
+    - on hold
+    - discussion
+    - to do