Replace usage of deprecated `grpc.Dial()`/`grpc.DialContext()` methods
with `grpc.NewClient()`. Also remove usage of `grpc.WithBlock()`,
`grpc.FailOnNonTempDialError()`, and `grpc.WithReturnConnectionError()`
options.

The combination of these changes results in a couple behavioral changes
when setting up gRPC clients:

1. gRPC will no longer dial when creating the client. Instead, it will
wait until the client is used for the first time with an RPC invocation.

2. gRPC uses the DNS resolver by default when building the
`*grpc.ClientConn` using `grpc.NewClient()`, whereas previously it used
to resolve addresses the `passthrough` resolver by default. The result
of this change in behavior is that for any invocations of
`grpc.Dial()`/`grpc.DialContext()` that did not specify a URI scheme,
gRPC now implicitly tries to resolve the address passed to
`grpc.NewClient()` using DNS. This breaks some assumptions in the code.
The workaround to preserve the previous address resolution behavior is
to prepend addresses with no scheme defined with the resolver URI scheme
`passthrough:`.

Also refactored some test-related code in `cmd/spire-server/cli/common`
into a new `test/clitest` package, since it is not intended
for use in production code.

Fixes spiffe#5152.

Signed-off-by: Ryan Turner <[email protected]>

Replace usage of deprecated `grpc.Dial()`/`grpc.DialContext()` methods
with `grpc.NewClient()`. Also remove usage of `grpc.WithBlock()`,
`grpc.FailOnNonTempDialError()`, and `grpc.WithReturnConnectionError()`
options.

The combination of these changes results in a couple behavioral changes
when setting up gRPC clients:

1. gRPC will no longer dial when creating the client. Instead, it will
wait until the client is used for the first time with an RPC invocation.

2. gRPC uses the DNS resolver by default when building the
`*grpc.ClientConn` using `grpc.NewClient()`, whereas previously it used
to resolve addresses the `passthrough` resolver by default. The result
of this change in behavior is that for any invocations of
`grpc.Dial()`/`grpc.DialContext()` that did not specify a URI scheme,
gRPC now implicitly tries to resolve the address passed to
`grpc.NewClient()` using DNS. This breaks some assumptions in the code.
The workaround to preserve the previous address resolution behavior is
to prepend addresses with no scheme defined with the resolver URI scheme
`passthrough:`.

Also refactored some test-related code in `cmd/spire-server/cli/common`
into a new `test/clitest` package, since it is not intended
for use in production code.

Fixes spiffe#5152.

Signed-off-by: Ryan Turner <[email protected]>