chore: remove webhooks after exiting npx pepr dev

[cmwylie19]

Description

This clears up issue 739 and removes the webhooks by listening for SIGINT on the process and listening for close on the program (child process) and upon receiving the signal removing the webhooks with a Promise.all.

Test:

# in one terminal
$> npm test 
$> cd pepr-test-module
$> npx pepr dev --confirm
# in another terminal
$> k get mutatingwebhookconfiguration,validatingwebhookconfiguration -oyaml # should be two
# HIT CTRL+C IN TERMINAL 1
$> k get mutatingwebhookconfiguration,validatingwebhookconfiguration -oyaml # should be 0

Related Issue

Fixes #739

Relates to #

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Other (security config, docs update, etc)

Checklist before merging

• Test, docs, adr added or updated as needed
• Contributor Guide Steps followed

[btlghrants]

As we covered in review, this cleans up what it can & leaves only what we can't be sure pepr:dev created. So long as we add a note in the docs somewhere -- something to the effect of "clean up pepr-system namespace and/or peprstore CRD by hand" -- I'll approve.

[btlghrants]

Tried to add some more context about why we're not auto-deleting those 2 things / make the items a user'd have to manually-delete a little more obvious through highlighting & bulleting.

[btlghrants]

Yep, LG.