Add a bot that closes stale issues

[l0rd]

Is your task related to a problem? Please describe.

We currently have more than 1k opened issues but most are not active since months / years. Going through all the issues to identifies the ones that are still relevant is not something we are able to manage.

Describe the solution you'd like

Setup a bot that runs daily and check if there are any issues that are inactive for more than 6 months. If that's a case it should comment on the issue with a warning that it will be closed if there is no action within the next week and close the issue the week after if there is still no activity.

[gorkem]

I favour the lifecycle/* labels of k8s. lifecycle/stale marks issues to be auto-closed soon and lifecycle/rotten marks auto-closed. One can protect an issue with lifecycle/frozen

[benoitf]

tell me if that is ok with you: (message + label)

I only applied on a single issue for now:
#3281 (comment)

[benoitf]

cc @l0rd @gorkem

[l0rd]

It's ok for me. Do you know if we can change che-bot logo?

[benoitf]

I'll Ask eclipse webmaster. You want eclipse che logo as avatar ?

[benoitf]

for che-bot avatar, done:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=550792

[l0rd]

@benoitf thanks

[benoitf]

bot is enabled

[gorkem]

@benoitf slash commands does not seem to work well. I encounter many cases where bot does not remove the label. I think we need to enable the webhooks.