controller: remove remaining parts of the controller

Removes all references to the controller and moves the remaining
sections of code to other packages.

Processes has been moved to monitor where it is used and the data
structs have been removed so buildflags is used directly. The controller
build function has been moved to the commands package.

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

util/buildflags/ssh.go

@@ -6,7 +6,6 @@ import (
 	"slices"
 	"strings"
 
-	controllerapi "github.com/docker/buildx/controller/pb"
 	"github.com/moby/buildkit/util/gitutil"
 )
 
@@ -31,18 +30,6 @@ func (s SSHKeys) Normalize() SSHKeys {
 	return removeSSHDupes(s)
 }
 
-func (s SSHKeys) ToPB() []*controllerapi.SSH {
-	if len(s) == 0 {
-		return nil
-	}
-
-	entries := make([]*controllerapi.SSH, len(s))
-	for i, entry := range s {
-		entries[i] = entry.ToPB()
-	}
-	return entries
-}
-
 type SSH struct {
 	ID    string   `json:"id,omitempty" cty:"id"`
 	Paths []string `json:"paths,omitempty" cty:"paths"`
@@ -70,13 +57,6 @@ func (s *SSH) String() string {
 	return b.String()
 }
 
-func (s *SSH) ToPB() *controllerapi.SSH {
-	return &controllerapi.SSH{
-		ID:    s.ID,
-		Paths: s.Paths,
-	}
-}
-
 func (s *SSH) UnmarshalJSON(data []byte) error {
 	var v struct {
 		ID    string   `json:"id,omitempty"`
@@ -103,8 +83,8 @@ func (s *SSH) UnmarshalText(text []byte) error {
 	return nil
 }
 
-func ParseSSHSpecs(sl []string) ([]*controllerapi.SSH, error) {
-	var outs []*controllerapi.SSH
+func ParseSSHSpecs(sl []string) ([]*SSH, error) {
+	var outs []*SSH
 	if len(sl) == 0 {
 		return nil, nil
 	}
@@ -118,7 +98,7 @@ func ParseSSHSpecs(sl []string) ([]*controllerapi.SSH, error) {
 		if err := out.UnmarshalText([]byte(s)); err != nil {
 			return nil, err
 		}
-		outs = append(outs, out.ToPB())
+		outs = append(outs, &out)
 	}
 	return outs, nil
 }