We're currently sending `referrer` with path for image/bookmark
requests. We shouldn't do that as it exposes the rooms to other servers.
## `<img>`
- `<img>` tags have the right referrerpolicy to be
`strict-origin-when-cross-origin`:
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#referrerpolicy
- _however_, because we use React, it looks like react creates a raw DOM
node and adds properties one by one and it loses the default
referrerpolicy it would otherwise get! So, in `BookmarkShapeUtil` we
explicitly state the `referrerpolicy`
- `background-image` does the right thing 👍
- _also_, I added this to places we do programmatic `new Image()`
## `fetch`
- _however_, fetch does not! wtf.
https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
it's almost a footnote in this section of the docs
(https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#supplying_request_options)
that `no-referrer-when-downgrade` is the default.
## `new Image()`
ugh, but _also_ doing a programmatic `new Image()` doesn't do the right
thing and we need to set the referrerpolicy here as well
### Change Type
<!-- ❗ Please select a 'Scope' label ❗️ -->
- [x] `sdk` — Changes the tldraw SDK
- [x] `dotcom` — Changes the tldraw.com web app
- [ ] `docs` — Changes to the documentation, examples, or templates.
- [ ] `vs code` — Changes to the vscode plugin
- [ ] `internal` — Does not affect user-facing stuff
<!-- ❗ Please select a 'Type' label ❗️ -->
- [x] `bugfix` — Bug fix
- [ ] `feature` — New feature
- [ ] `improvement` — Improving existing features
- [ ] `chore` — Updating dependencies, other boring stuff
- [ ] `galaxy brain` — Architectural changes
- [ ] `tests` — Changes to any test code
- [ ] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
- [ ] `dunno` — I don't know
### Test Plan
1. Test on staging that referrer with path isn't being sent anymore.
### Release Notes
- Security: fix referrer being sent for bookmarks and images.
b7bc2dbbce