Improve stack traces thrown from client functions

[Half-Shot]

Currently, stack traces are rather unhelpful when thrown from MatrixClient functions:

     Error: M_FORBIDDEN: Application service has not registered this user (@redacted)
      at /redacted/matrix-bot-sdk/lib/http.js:105:19
      at Generator.next (<anonymous>)
      at fulfilled (/redacted/matrix-bot-sdk/lib/http.js:5:58)
      at processTicksAndRejections (internal/process/task_queues.js:95:5)

This doesn't really give away where the problem actually came from in the source. This PR does 3 things to resolve this:

• Throwing an error doHttpRequest directly, rather than inside the handler function for request. This reduces the amount of cruft in the stack trace. This did require a bit of rejiggling, and also fixed a bug introduced where non-JSON non-200 bodies would cause issues.
• Using ES2020 for Typescript compilation. This project was on 2015, which meant that async funcs were wrapped in generators. I'd imagine this also comes with a performance improvement, but at the very least using native async gives node a chance to report something sensible.
• Most importantly: The metrics decorator functions were obscuring the error somewhat with the way they handled calling their parent function. I believe the changes I've introduced don't come with any functionality changes, have definitely improved the stack traces and have tripped down the LOC for each decorator.

The new stack traces look like:

DEBUG 15:46:00:404 [MatrixHttpClient] (REQ-1) PUT http://localhost:8008/_matrix/client/r0/rooms/NotARoom/send/m.room.message/1651761960404__inc1
ERROR 15:46:00:420 [MatrixHttpClient (REQ-1)] { errcode: 'M_FORBIDDEN', error: 'Unknown room' }
ERROR 15:46:00:442 [App] BridgeApp encountered an error and has stopped: MatrixError: M_FORBIDDEN: Unknown room
    at doHttpRequest (/reacted/lib/http.js:95:15)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at MatrixClient.descriptor.value (/reacted/lib/metrics/decorators.js:21:26)
    at MatrixClient.descriptor.value (/reacted/lib/metrics/decorators.js:21:26)
    at MatrixClient.descriptor.value (/reacted/lib/metrics/decorators.js:21:26)
    at MatrixClient.descriptor.value (/reacted/lib/metrics/decorators.js:21:26)
    at MatrixClient.descriptor.value (/reacted/lib/metrics/decorators.js:21:26)
    at Bridge.start (/home/will/git/matrix-hookshot/src/Bridge.ts:91:9)
    at start (/home/will/git/matrix-hookshot/src/App/BridgeApp.ts:39:5) {
  body: { errcode: 'M_FORBIDDEN', error: 'Unknown room' },
  statusCode: 403,
  errcode: 'M_FORBIDDEN',
  error: 'Unknown room',
  retryAfterMs: undefined
}

Which while introduce a bit more cruft when several decorators are used in a chain, it also gives you a hint as to where the function call originated from.

[tadzik]

+1 from me, as this is currently a huge PITA when debugging.

[turt2live]

overall lgtm