Implement CreatePersonalAccessToken RPC

[easyCZ]

Implement https://github.com/gitpod-io/gitpod/blob/main/components/public-api/gitpod/experimental/v1/tokens.proto#L49

We will need to do the following:

• Add a migration to create the new table to store these tokens [db] Create d_b_personal_access_token #14724
• [db] Move db models to go-db module #14770
• Define a DB model in Go, under the public-api-server/pkg/db - see examples in usage/pkg/db [public api] personal access token db model #14740
• [public-api] Create Personal Access Token implementation #14846
• Handle scopes

• Follow instructions on how create behaves from this RFC
  • Strong unit test coverage
  • The Create handler must first check if the user is permitted to perform the "create" action - see Implement server API to check if a User has permission to operate on a token #14619

Given this change touches multiple different components, it's strongly recommended to create PRs incrementally and land them.