connection: eliminate String method variants

After contemplating this for a little bit, there's no point in exposing
these separately from the plain variants. Even nats.c internally calls
its plain variants after calling `strlen` on the input. Zig benefits
from having nicer pointer types than C, so we get "string" handling
for free from the fact that the standard variants take slices anyway.

examples/request_reply.zig

@@ -15,7 +15,7 @@ fn onMessage(
     });
 
     if (message.getReply()) |reply| {
-        connection.publishString(reply, "salutations") catch @panic("HELP");
+        connection.publish(reply, "salutations") catch @panic("HELP");
     }
 
     userdata.* = true;
@@ -30,7 +30,7 @@ pub fn main() !void {
     defer subscription.destroy();
 
     while (!done) {
-        const reply = try connection.requestString("channel", "greetings", 1000);
+        const reply = try connection.request("channel", "greetings", 1000);
         defer reply.destroy();
 
         std.debug.print("Reply \"{s}\" got message: {s}\n", .{

src/connection.zig

@@ -244,16 +244,6 @@ pub const Connection = opaque {
         ).raise();
     }
 
-    pub fn publishString(
-        self: *Connection,
-        subject: [:0]const u8,
-        message: [:0]const u8,
-    ) Error!void {
-        return Status.fromInt(
-            nats_c.natsConnection_PublishString(@ptrCast(self), subject.ptr, message.ptr),
-        ).raise();
-    }
-
     pub fn publishMessage(self: *Connection, message: *Message) Error!void {
         return Status.fromInt(
             nats_c.natsConnection_PublishMsg(@ptrCast(self), @ptrCast(message)),
@@ -277,22 +267,6 @@ pub const Connection = opaque {
         ).raise();
     }
 
-    pub fn publishRequestString(
-        self: *Connection,
-        subject: [:0]const u8,
-        reply: [:0]const u8,
-        message: [:0]const u8,
-    ) Error!void {
-        return Status.fromInt(
-            nats_c.natsConnection_PublishRequestString(
-                @ptrCast(self),
-                subject.ptr,
-                reply.ptr,
-                message.ptr,
-            ),
-        ).raise();
-    }
-
     pub fn request(
         self: *Connection,
         subject: [:0]const u8,
@@ -313,25 +287,6 @@ pub const Connection = opaque {
         return status.toError() orelse response;
     }
 
-    pub fn requestString(
-        self: *Connection,
-        subject: [:0]const u8,
-        req: [:0]const u8,
-        timeout: i64,
-    ) Error!*Message {
-        var response: *Message = undefined;
-
-        const status = Status.fromInt(nats_c.natsConnection_RequestString(
-            @ptrCast(&response),
-            @ptrCast(self),
-            subject.ptr,
-            req.ptr,
-            timeout,
-        ));
-
-        return status.toError() orelse response;
-    }
-
     pub fn requestMessage(
         self: *Connection,
         req: *Message,