Re-introduce Sentry CLI

[Lms24]

After realizing that achieving feature parity with the Sentry WebPack Plugin and at the same time replacing Sentry CLI underneath would be an enourmous amount of work, we decided to prioritize feature parity. Consequently, we're re-introducing Sentry CLI.

Tasks:

• Add the CLI package as a dependency and create a CLI instance ref(core): Add Sentry CLI #86
• ref(core): Replace release detection with Sentry CLI release detection #87
• ref(core): Use Sentry CLI for sourcemaps upload #88
• Revisit create release and other partially implemented pipeline stages
  • ref(core): Use Sentry-CLI to finalize release #90
  • ref(core): Use Sentry CLI for artifact deletion #92
  • ref(core): Use Sentry CLI to create new release #93

ref: #50