Fixes for TLS termination

[chris48s]

This is one part of the jigsaw to get badges/shields#8424 sorted.

The first one is a bit of a silly issue. ScoutCamp doesn't recognise -----BEGIN PRIVATE KEY----- as the start of a private key so it falls back to trying to load it from file. This PR loosens the regex.

The second one is: Once I got ScoutCamp using the CloudFlare keys, I started hitting this error:

ewr [info] node:internal/buffer:959
ewr [info] super(bufferOrLength, byteOffset, length);
ewr [info] ^
ewr [info] RangeError: Invalid typed array length: -4095
ewr [info] at new Uint8Array (<anonymous>)
ewr [info] at new FastBuffer (node:internal/buffer:959:5)
ewr [info] at Handle.onStreamRead [as onread] (node:internal/stream_base_commons:189:19)
ewr [info] at Stream.<anonymous> (/usr/src/app/node_modules/spdy/node_modules/handle-thing/lib/handle.js:120:12)
ewr [info] at Stream.emit (node:events:532:35)
ewr [info] at Stream.emit (node:domain:475:12)
ewr [info] at endReadableNT (/usr/src/app/node_modules/readable-stream/lib/_stream_readable.js:1010:12)
ewr [info] at processTicksAndRejections (node:internal/process/task_queues:83:21)

I traced that to this issue: spdy-http2/node-spdy#363

and updating spdy/handle-thing seems to do the trick. As far as I can tell, the only breaking change for spdy 3 --> 4 is dropping older node versions. Node-spdy itself seems to be unmaintaned and there is no changelog, so I had to read the diff.

Everything on this repo is bad and old and unloved so there is no CI, but I've run the tests locally. They all pass. Perhaps more importantly I've run the shields test suite against a copy of shields with this scoutcamp installed into it and they all pass, so that's good.

I probably should have had a look at socket.io while I am working on this repo, but I haven't. It can wait.

Obviously none of us have great detailed insight into this library, but anything else I should think about here?

[calebcartwright]

Oof, good find