Title: [Technical review] Add BiDi network pages: addIntercept, continueRequest, failRequest, removeIntercept

Description

• Added pages for the following commands of the network module:
  • network.addIntercept
  • network.continueRequest
  • network.failRequest
  • network.removeIntercept
• Added an "Intercepts" section to the network module landing page.

The pages link to the event pages from #46141 and to network.setExtraHeaders from #46140, so this PR should merge after those two.

Every example was run against Firefox Nightly 159 and Chrome 155 (through ChromeDriver) with a local server.

Spec links

• https://w3c.github.io/webdriver-bidi/#command-network-addIntercept
• https://w3c.github.io/webdriver-bidi/#command-network-continueRequest
• https://w3c.github.io/webdriver-bidi/#command-network-failRequest
• https://w3c.github.io/webdriver-bidi/#command-network-removeIntercept

Related issue

Doc issue: mdn/mdn#851

Compat quirks worth looking into:

• Compat data for the continueRequest parameters in Firefox. All three come from my test run:
  • url: for a fetch(), the rewritten request reaches the new URL and the events report a 200 from it, but the page's fetch() rejects with AbortError: The operation was aborted. A navigation with a rewritten URL works. BCD shows Firefox's url parameter as supported since 133. cc @whimboo for the compat sheet update.
  • headers: Firefox sends only the headers in the list, so a list without Host produces a request with no Host header (my server answered 400). Chrome still sends Host, Cookie, User-Agent and its other network headers. BCD shows Firefox's headers parameter as supported. cc @whimboo for the compat sheet update.
  • body: with a longer body for a POST request, Firefox keeps the original Content-Length, so the server receives a truncated body. Chrome sends the new length. BCD shows Firefox's body parameter as supported. cc @whimboo for the compat sheet update.