feat: add client/server version check mechanism to gRPC calls (#260)

* Add version check mechanism to gRPC calls

* Use semver not semver/v3

* Give dev builds a special "infinite" version number (999.0.0-dev)

* Handle no metadata on grpc call correctly for version check

* Move versioncheck package to root pkg/ from pkg/api/ since it is shared by both pkg/api/ and pkg/client/

* Only show "no daemon version" warning once

* Append version headers to metadata, not overwrite...

* Unit tests on versioncheck logic

* Move SetHeader to the ServerStream in ServerStreamInterceptor

* Go modernizer nits: interface{} -> any

* Use more conventional gRPC header names for version/min-versions

* Add TODO notes on checkDaemonVersionInResponse and related code that can be removed eventually after transition to version checking client/daemons

* Use testify for testing assertions

* Add explanatory comments on MinCLIVersion and MinDaemonVersion

---------

Co-authored-by: Pasha Sviderski <me@psviderski.name>

pkg/client/connector/sshcli.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	"github.com/docker/cli/cli/connhelper/commandconn"
+	"github.com/psviderski/uncloud/pkg/versioncheck"
 	"golang.org/x/net/proxy"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
@@ -77,6 +78,8 @@ func (c *SSHCLIConnector) Connect(ctx context.Context) (*grpc.ClientConn, error)
 		"passthrough:///", // Dummy target since we're using a custom dialer.
 		grpc.WithTransportCredentials(insecure.NewCredentials()),
 		grpc.WithDefaultServiceConfig(defaultServiceConfig),
+		grpc.WithUnaryInterceptor(versioncheck.ClientUnaryInterceptor),
+		grpc.WithStreamInterceptor(versioncheck.ClientStreamInterceptor),
 		grpc.WithContextDialer(func(ctx context.Context, _ string) (net.Conn, error) {
 			dialArgs := append(c.buildSSHArgs(), "uncloudd", "dial-stdio")
 			if c.config.SockPath != "" {