Add support for room aliases

[MadLittleMods]

Add support for room aliases. Also does friendly redirects if you don't exactly use the right URL pattern. For example, if you paste the full room ID with the ! like /roomid/!foo:bar, it will properly redirect you to /roomid/foo:bar. It also does this sort of thing for URL encoded room ID's and aliases.

Fix #25

[...] we can use a schemaless Matrix URI (matrix://) which doesn't include the sigils so there is no URL encoding issue.

The URL's for the archive end up looking like:

• Room alias: /r/matrix:matrix.org/date/2022/06/28
• Room ID: /roomid/OGEhHVWSdvArJzumhm:matrix.org/date/2022/06/28

Todo

• Update links on room directory to reflect alias usage now
• Add client-side redirects when someone just pastes a room alias on the end of the domain
  • Split out to Add support for client-side room alias hash # redirects to the correct URL #111
• If someone visits via /roomid/..., we shouldn't switch them over to room alias or vice versa
• Add tests for visiting room by room ID or room alias
• Add tests for room ID honest mistake redirects:
  • /roomid/!HBehERstyQBxyJDLfR:my.synapse.server -> /roomid/HBehERstyQBxyJDLfR:my.synapse.server
  • /roomid/!HBehERstyQBxyJDLfR:my.synapse.server/date/2022/09/20?via=my.synapse.server -> /roomid/HBehERstyQBxyJDLfR:my.synapse.server/date/2022/09/20?via=my.synapse.server
  • /!HBehERstyQBxyJDLfR:my.synapse.server -> /roomid/HBehERstyQBxyJDLfR:my.synapse.server
  • We can't test room alias honest mistakes because those redirects happen client-side
• Test with URI encoded values %23test-room1%3Amy.synapse.server, !HBehERstyQBxyJDLfR%3Amy.synapse.server

Dev notes

const nowDate = new Date();

// Warn if it's close to the end of the UTC day. This test could be a flakey
// and cause a failure if the room was created just before midnight (UTC) and
// this timestamp comes after midnight. The redirect would want to go to the
// day before when the latest event was created instead of the `nowDate` we
// expected in the URL's.
//
// We could lookup the date of the latest event to use the `origin_server_ts`
// from ourselves which may be less faff than this big warning but 🤷
const utcMidnightOfNowDay = Date.UTC(
  nowDate.getUTCFullYear(),
  nowDate.getUTCMonth(),
  nowDate.getUTCDate() + 1
);
if (utcMidnightOfNowDay - nowDate.getTime() < 30 * 1000 /* 30 seconds */) {
  // eslint-disable-next-line no-console
  console.warn(
    `Test is being run at the end of the UTC day. This could result in a flakey ` +
      `failure where the room was created before midnight (UTC) but the \`nowDate\` ` +
      `was after midnight meaning our expected URL's would be a day ahead. Since ` +
      `this is an e2e test we can't control the date/time exactly.`
  );
}