Tests for Testimony Detail Page

**Goal**
We want to be able to automatically test the Testimony Detail page to build confidence in the basic functioning of the site after deploys.

**Success Criteria:**
- Add a Test to confirm that the Testimony Detail page renders as expected
- This likely doesn't need to be a full E2E test just yet - unit tests confirming the page renders correctly should be fine
- Will likely need to detect the presence of:
- Bill Title
- Testimony stance (endore/neutral/oppose) and text
- Add Testimony action (for logged out user or user who has not submitted testimony)
- Edit Testimony action (for user who has submitted testimony)
- Revision History

**Exclusions**
- Likely doesn't need to be an E2E test just yet - this seems like it could be a good case for building out our unit test suite
- There was a previous bug in navigating to the Testimony Detail page due to faulty link construction - we want to test the case automatically going forward, bu the issue there was in the originating page, so this E2E test case will be covered in the Browse Testimonies tests and not here.