Add APIMeta fields related to SSH keys

[twpayne]

As described in https://docs.github.com/en/rest/reference/meta.

[gmlewis]

Thank you, @twpayne ! Please run go generate ./... and push the changes to the PR.
See CONTRIBUTING.md for more information.

[twpayne]

🙈 Doh! Sorry about missing that. In updating this I also deliberately made the faux pas of modifying the original commit with a forced push, but I hope it's OK in this case as the extra changes are automatically generated.

[codecov]

Codecov Report

Merging #2293 (2ec5da9) into master (2981e4f) will not change coverage.
The diff coverage is n/a.

@@ Coverage Diff @@## master #2293 +/- ##
=======================================
Coverage 97.84% 97.84% =======================================
Files 115 115 Lines 10378 10378 =======================================
Hits 10154 10154 Misses 156 156 Partials 68 68 

Impacted Files	Coverage Δ
github/misc.go	96.36% <ø> (ø)

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[gmlewis]

Thank you, @twpayne !
LGTM.
Merging.