Add GitHub !issue parser

[SapphicFire]

Description

#292 described a need to create a parser that can create GitHub issues from Slack. This PR includes this parser, and contains support for a GitHub App, SNDevs Slacker Issue Reporter.

Resolves #292

Usage

!issue [repo name or shorthand] description

Example:

!issue Slacker Add a new issue

The description will be placed in both the title and body, with the title shortened if it overruns a character limit (currently 60)

Set up

In order to activate the !issue parser, the following steps must occur

On GitHub:

• Request the install of SNDevs Slacker Issue Reporter in the ServiceNow Dev Program Organisation
• Approve the above install request (@earlduque or other Owner of org)

On DPR:

• Create slackerbot.issueapp.install_id property with app installation ID in the Global scope
• Create slackerbot.issueapp.id property with app client ID in the Global scope
• Create sys_certificate record and attach JKS trust store
• Create jwt_keystore_aliases record and associate above X.509 Certificate record
• Create jwt_provider record and associate above JWT Key record
• Create slackerbot.issueapp.provider property with sys_id of above JWT Provider record
• Verify cross-scope privileges and module access policies apply correctly on first use

[SapphicFire]

I have organised the configuration on the DPR side with the exception of the installation ID as we won't know that until the install request is approved.

[chelming]

should all cases of !issue Slacker be replaced with !issue SlackerBot? nm. I see the map now. https://github.com/ServiceNowDevProgram/SlackerBot/pull/369/files#diff-03d020202eeb37fb76424637351d5f88a5562463a22a7f7e50963b27df41aabfR85-R95

[SapphicFire]

should all cases of !issue Slacker be replaced with !issue SlackerBot? nm. I see the map now. https://github.com/ServiceNowDevProgram/SlackerBot/pull/369/files#diff-03d020202eeb37fb76424637351d5f88a5562463a22a7f7e50963b27df41aabfR85-R95

I figured nobody would enjoy typing out the GenAi repo name in full

[earlduque]

Is the underlying code of https://github.com/apps/sndevs-slacker-issue-reporter exposed anywhere? I need to do a full review of it before installing it on this organization (which has full security monitoring internally, so I wanna make sure(

[SapphicFire]

There isn't any code because GitHub Apps function as a permissions and authentication vehicle.

Happy to do a video walkthrough or jump on a call with you to review?

[earlduque]

we good. you rock

[chelming]

can the app owner be set to an org or does that take some sort of certification/review?