DevTools 91/90 content additions

[AaronForinton]

From: https://developer.chrome.com/blog/new-in-devtools-91/

• [ ] Hover on a Web Vitals marker in the Performance panel to understand what's the indicator about - whether the performance is good, needs improvement, or poor. — would be /docs/devtools/performance/reference/ -
• [x] bugged: Ticket at https://bugs.chromium.org/p/chromium/issues/detail?id=1423967
• [x] Image previews in the Elements panel now displays more information on the image - rendered size, rendered aspect ratio, intrinsic size, intrinsic aspect ratio, and file size. — docs/devtools/dom
• [x] A new network conditions button is added in the Network panel. Click on it to open the Network conditions tab. A new Accepted Content-Encodings option is added to the Network conditions tab. Configure it to test if server responses are encoded correctly in browsers that do not support gzip, brotli, or other future Content-Encodings. — docs/devtools/network/reference
• [ ] You can now delete trust tokens with the new delete button in the Trust tokens pane, under the Application panel. -> Maybe a new page on trust tokens encompassing updates in previous versions too. -> now ‘private state tokens’, panel was introduced in 90 and 89
• [x] Chromium issue raised: https://bugs.chromium.org/p/chromium/issues/detail?id=1423684

To do: Replace screenshots

[chrome-devrel-infra[bot]]

:white_check_mark: Preview (static) for commit f60aa8a5bc7cf75a906fb28bd4f60d334c45fec5 available at https://pr-5631-static-dot-dcc-staging.uc.r.appspot.com/.

The following pages likely changed with this PR:

• https://pr-5631-static-dot-dcc-staging.uc.r.appspot.com/docs/devtools/dom/
• https://pr-5631-static-dot-dcc-staging.uc.r.appspot.com/docs/devtools/lighthouse/
• https://pr-5631-static-dot-dcc-staging.uc.r.appspot.com/docs/devtools/network/reference/
• https://pr-5631-static-dot-dcc-staging.uc.r.appspot.com/docs/devtools/storage/private-state-tokens/

[AaronForinton]

@sofiayem Let me know what you think of the changes I've made so far and I'll continue.

[AaronForinton]

cc @rachelandrew I've added myself to the dcc authors list in this PR