Feature Request: Customer Project Metadata

### Problem Statement

Hello team, submitting this feature request on behalf of one of our users:

Summary:
- Allow an optional custom metadata on projects that can be reference and updated via the UI and API.

Problem Statement:
Operating a large number of sentry projects (3,500), I currently lack the ability to reference/link this projects to my internal registry of services.
When reviewing projects in sentry its difficult for me to know what the underlying ownership, deployments, and other information that is stored in our registry system.

### Solution Brainstorm


Add a metadata/custom-data field for each project that can be updated via the UI and API. This would allow for customers to set data that is later referenced as needed.
This would not be a required field, and TEXT is preferred to allow me to store either a single URI or to store json or yaml with information about the project.

### Product Area

Settings - Projects

┆Issue is synchronized with this [Jira Improvement](https://getsentry.atlassian.net/browse/FEEDBACK-2279) by [Unito](https://www.unito.io)