Speed up building plugins binaries on CI

[mszostok]

Description

For release job:

1. Build Botkube core and Botkube plugins in parallel (start the GoReleaser job simultaneously)
2. Use the gh CLI do publish draft release with all assets generated by the 1st step.

For PR job:

1. Build Botkube core and Botkube plugins in parallel (start the GoReleaser job simultaneously)
   • extract the

     botkube/.github/workflows/pr-build.yaml

     Line 207 in 7488728

     - name: Build all plugins into dist directory

     and run it simultaneously with

     botkube/.github/workflows/pr-build.yaml

     Line 34 in 7488728

     save-image:

     and save binaries as GitHub artifact.
2. Use the generated artifacts in the e2e tests

Reason

Reduce time to merge and time to release (improvement by ~5-6 minutes, more if we had more plugins).