[ENH] Enable getting a collection by CRN (#5244)

## Description of changes

_Summarize the changes made by this PR._

- Improvements & Bug fixes
  - N/A
- New functionality
- Adds a new endpoint that enables getting a collection by CRN
(`<tenant_resource_name>:<database_name>:<collection_name>`)

## Test plan

_How are these changes tested?_

- [ ] Tests pass locally with `pytest` for python, `yarn test` for js,
`cargo test` for rust

## Migration plan

_Are there any migrations, or any forwards/backwards compatibility
changes needed in order to make sure this change deploys reliably?_

## Observability plan

_What is the plan to instrument and monitor this change?_

## Documentation Changes

_Are all docstrings for user-facing APIs updated if required? Do we need
to make documentation changes in the [docs
section](https://github.com/chroma-core/chroma/tree/main/docs/docs.trychroma.com)?_