Implement flag/config falue for GPG provider

utils/config.go

@@ -19,6 +19,7 @@ type ConfigStructure struct { // nolint: aligncheck
 	DepVerboseResolve      bool                             `json:"dependencyVerboseResolve"`
 	GpgDisableSign         bool                             `json:"gpgDisableSign"`
 	GpgDisableVerify       bool                             `json:"gpgDisableVerify"`
+	GpgProvider            string                           `json:"gpgProvider"`
 	DownloadSourcePackages bool                             `json:"downloadSourcePackages"`
 	SkipLegacyPool         bool                             `json:"skipLegacyPool"`
 	PpaDistributorID       string                           `json:"ppaDistributorID"`
@@ -79,6 +80,7 @@ var Config = ConfigStructure{
 	DepFollowRecommends:    false,
 	DepFollowAllVariants:   false,
 	DepFollowSource:        false,
+	GpgProvider:            "gpg",
 	GpgDisableSign:         false,
 	GpgDisableVerify:       false,
 	DownloadSourcePackages: false,

utils/config_test.go

@@ -30,6 +30,7 @@ func (s *ConfigSuite) TestSaveConfig(c *C) {
 
 	s.config.RootDir = "/tmp/aptly"
 	s.config.DownloadConcurrency = 5
+	s.config.GpgProvider = "gpg"
 
 	s.config.FileSystemPublishRoots = map[string]FileSystemPublishRoot{"test": {
 		RootDir: "/opt/aptly-publish"}}
@@ -64,6 +65,7 @@ func (s *ConfigSuite) TestSaveConfig(c *C) {
 		"  \"dependencyVerboseResolve\": false,\n"+
 		"  \"gpgDisableSign\": false,\n"+
 		"  \"gpgDisableVerify\": false,\n"+
+		"  \"gpgProvider\": \"gpg\",\n"+
 		"  \"downloadSourcePackages\": false,\n"+
 		"  \"skipLegacyPool\": false,\n"+
 		"  \"ppaDistributorID\": \"\",\n"+