Rebase on 1.22.12

[bwesterb]

Mostly trivial rebase. Add a fix of a time bomb.

 1:  ad6d8311cc =  1:  2453c27e89 Add README (#158)
 2:  f6c2818f00 <  -:  ---------- VERSION: add cf tag
 -:  ---------- >  2:  3aac0b5a06 VERSION: add cf tag
 3:  12d930db85 =  3:  8fb142dd30 cmd/go/internal/imports, go/build: add cfgo build tag
 4:  98209d8da8 =  4:  c48cc6b62b .github: add docker-compose.yaml and GitHub Action for CI
 5:  8846cd808b =  5:  6b690ad885 .github: replace upstream templates and CODE_OF_CONDUCT.md
 6:  885e769d30 =  6:  6f2e23240a cmd/api: ignore CF-specific API changes
 7:  10395434c5 =  7:  d418b6d0dd go/build: don't check dependencies of vendored circl library
 8:  b5d791215e =  8:  58f7ed4071 crypto/tls: expose inter-handshake timing via CFEventHandlerContextKey
 9:  32f83b78a3 =  9:  21ab11b08a crypto/tls: Add hybrid post-quantum key agreements
10:  f2bfd08e62 = 10:  876e2a8a9a crypto: add support for CIRCL signature schemes
11:  1169950a0d = 11:  be51d92cb3 crypto/tls: implement draft-ietf-tls-subcerts-10
12:  0e7b54069b = 12:  0d233aaebf crypto/tls: implement draft-ietf-tls-esni-13
13:  b935551fd7 = 13:  906b05c04d Set GOTOOLCHAIN to local to prevent auto-download of new Go
14:  d26ab7234d = 14:  bf686dc996 Add tls.Config.ClientCurveGuess to allow specifying which keyshares to send
15:  9f08975994 = 15:  4cdf9ea0d3 Use server's preferred key agreement
16:  f4334cdc0c = 16:  b00fc31866 Add dummy key agreement with codepoint 0xfe33 (#162)
17:  af19da5605 = 17:  420f18a277 Add support for X25519MLKEM768. (#179)
 -:  ---------- > 18:  8fe8844b34 metrics: use testTime instead of now, and make testTime increment.

(We will rebase on 1.24 in the near future btw—it will require some work unfortunately.)