chore(): migrate to github issues forms

[micalevisk]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Other... Please describe:

Just because GitHub issue forms looks nicer than the old issue templates, and also to enforce for sure some standard across issues in this repo.

What is the new behavior?

See them in action here: https://github.com/micalevisk/nest-cli/issues/new/choose

Pretty much the same as the ones in these others Nestjs's repos, with minor changes:

• https://github.com/nestjs/mapped-types
• https://github.com/nestjs/terminus
• https://github.com/nestjs/typeorm
• https://github.com/nestjs/axios
• https://github.com/nestjs/event-emitter
• https://github.com/nestjs/throttler
• https://github.com/nestjs/elasticsearch
• https://github.com/nestjs/schematics
• https://github.com/nestjs/jwt
• https://github.com/nestjs/config
• https://github.com/nestjs/passport
• https://github.com/nestjs/schedule
• https://github.com/nestjs/bull
• https://github.com/nestjs/serve-static
• https://github.com/nestjs/cqrs
• https://github.com/nestjs/graphql
• https://github.com/nestjs/swagger
• https://github.com/nestjs/nest

(yes, I'm targeting every repository listed above)

Does this PR introduce a breaking change?

[ ] Yes
[x] No

[kamilmysliwiec]

LGTM 🙌