proposal: x/crypto/ssh/knownhosts: create from ...io.Reader

[tg123]

knownhosts.New accept file on local disk only now, which is not flexible for parsing knowhosts inside memory or load from other media.

Proposal for new API

func NewFromReader(reader ...io.Reader) (ssh.HostKeyCallback, error)

to load knowhosts from io.Reader s

[ianlancetaylor]

CC @golang/security

[drakkan]

I like this proposal, just wondering if we should allow multiple readers similarly to knownhosts.New where we accept multiple files

[josharian]

Ping.

[tg123]

@drakkan multiple reader supported, could you please help to review?