grpc: Deprecate InitialWindowSize and introduce InitialStreamWindowSize

Part of #7923.

Since it has been two releases after #8283 is merged, we can
introduce InitialStreamWindowSize on both server and client, while
deprecating InitialWindowSize.

RELEASE NOTES:

* grpc: Introduce new ServerOption and ClientOption to set stream
window size without disabling BDP estimation.

* grpc: Behavior change in WithInitialWindowSize in ClientOption
and InitialWindowSize in ServerOption. Using these options will no
longer disable BDP estimation. To explicitly disable BDP estimation,
please use *StaticStreamWindowSize options.

* grpc: Mark WithInitialWindowSize for deprecation, to be replaced
with WithInitialStreamWindowSize in ClientOption. Similarly, for
InitialWindowSize inServerOption to be replaced with InitialStreamWindowSize.

Author: Pramodh-G

dialoptions.go

@@ -210,10 +210,13 @@ func WithReadBufferSize(s int) DialOption {
 // WithInitialWindowSize returns a DialOption which sets the value for initial
 // window size on a stream. The lower bound for window size is 64K and any value
 // smaller than that will be ignored.
+//
+// Deprecated: use WithInitialStreamWindowSize to set a stream window size without disabling
+// dynamic flow control.
+// Will be supported throughout 1.x.
 func WithInitialWindowSize(s int32) DialOption {
 	return newFuncDialOption(func(o *dialOptions) {
 		o.copts.InitialWindowSize = s
-		o.copts.StaticWindowSize = true
 	})
 }
 
@@ -223,10 +226,17 @@ func WithInitialWindowSize(s int32) DialOption {
 func WithInitialConnWindowSize(s int32) DialOption {
 	return newFuncDialOption(func(o *dialOptions) {
 		o.copts.InitialConnWindowSize = s
-		o.copts.StaticWindowSize = true
 	})
 }
 
+// WithInitialStreamWindowSize returns a DialOption which sets the value for
+// a initial window size on a stream. The lower bound for window size is 64K
+// and any value smaller than that will be ignored. Importantly, this does
+// not disable dynamic flow control.
+func WithInitialStreamWindowSize(s int32) DialOption {
+	return WithInitialWindowSize(s)
+}
+
 // WithStaticStreamWindowSize returns a DialOption which sets the initial
 // stream window size to the value provided and disables dynamic flow control.
 func WithStaticStreamWindowSize(s int32) DialOption {

server.go

@@ -278,10 +278,13 @@ func ReadBufferSize(s int) ServerOption {
 
 // InitialWindowSize returns a ServerOption that sets window size for stream.
 // The lower bound for window size is 64K and any value smaller than that will be ignored.
+//
+// Deprecated: use InitialStreamWindowSize to set a stream window size without disabling
+// dynamic flow control.
+// Will be supported throughout 1.x.
 func InitialWindowSize(s int32) ServerOption {
 	return newFuncServerOption(func(o *serverOptions) {
 		o.initialWindowSize = s
-		o.staticWindowSize = true
 	})
 }
 
@@ -290,10 +293,16 @@ func InitialWindowSize(s int32) ServerOption {
 func InitialConnWindowSize(s int32) ServerOption {
 	return newFuncServerOption(func(o *serverOptions) {
 		o.initialConnWindowSize = s
-		o.staticWindowSize = true
 	})
 }
 
+// InitialStreamWindowSize returns a ServerOption that sets the window size for a stream.
+// THe lower bound for a window size is 64K, and any value smaller than that will be ignored.
+// Importantly, this does not disable dynamic flow control.
+func InitialStreamWindowSize(s int32) ServerOption {
+	return InitialWindowSize(s)
+}
+
 // StaticStreamWindowSize returns a ServerOption to set the initial stream
 // window size to the value provided and disables dynamic flow control.
 // The lower bound for window size is 64K and any value smaller than that