Avoid 'transport closing' errors on client side

[kuba--]

Signed-off-by: kuba-- kuba@sourced.tech
Addresses: bblfsh/go-client#124
bblfsh/go-client#124 (comment)

This PR sets grpc.KeepaliveEnforcementPolicy to common server options, by decreasing MinTime from 5 to 1 minute and setting PermitWithoutStream to true.

EnforcementPolicy is used to set keepalive enforcement policy on the
server-side. Server will close connection with a client that violates this policy.

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This change is 

[dennwc]

Reviewed 3 of 3 files at r1.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @bzz, @creachadair, @kuba--, and @ncordon)

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daemon/daemon.go, line 64 at r1 (raw file):

		}),
	)
	opts = append(opts, commonOpt...)

We need to reverse it then: append user options (opts) to the end of commonOpt, so it's possible to override those defaults.

[kuba--]

Reviewable status: 2 of 3 files reviewed, 1 unresolved discussion (waiting on @bzz, @creachadair, @dennwc, and @ncordon)

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daemon/daemon.go, line 64 at r1 (raw file):

Previously, dennwc (Denys Smirnov) wrote…

We need to reverse it then: append user options (opts) to the end of commonOpt, so it's possible to override those defaults.

Done.

[dennwc]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @bzz, @creachadair, and @ncordon)

[creachadair]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @bzz, @creachadair, and @ncordon)

[ncordon]

LGTM!

[ncordon]

Reviewed 2 of 3 files at r1, 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @bzz)

[dennwc]

Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @bzz)