Add config for setting search_min_length capability

This adds the "search_min_length" setting to the frontend service which
allows to set the search_min_length capabilty which is e.g. used by
web.

Partial: owncloud#547

services/frontend/pkg/config/config.go

@@ -32,6 +32,7 @@ type Config struct {
 	UploadHTTPMethodOverride string `yaml:"upload_http_method_override" env:"FRONTEND_UPLOAD_HTTP_METHOD_OVERRIDE" desc:"Advise TUS to replace PATCH requests by POST requests."`
 	DefaultUploadProtocol    string `yaml:"default_upload_protocol" env:"FRONTEND_DEFAULT_UPLOAD_PROTOCOL" desc:"The default upload protocol to use in the frontend (e.g. tus)."`
 	EnableResharing          bool   `yaml:"enable_resharing" env:"FRONTEND_ENABLE_RESHARING" desc:"Enables the support for resharing in the frontend."`
+	SearchMinLength          int    `yaml:"search_min_length" env:"FRONTEND_SEARCH_MIN_LENGTH" desc:"Minimum number of characters to enter before starting a search for Sharees."`
 
 	PublicURL string `yaml:"public_url" env:"OCIS_URL;FRONTEND_PUBLIC_URL" desc:"The public facing URL of the oCIS frontend."`
 

services/frontend/pkg/config/defaults/defaultconfig.go

@@ -39,6 +39,7 @@ func DefaultConfig() *config.Config {
 		UploadHTTPMethodOverride: "",
 		DefaultUploadProtocol:    "tus",
 		EnableResharing:          true,
+		SearchMinLength:          3,
 		Checksums: config.Checksums{
 			SupportedTypes:      []string{"sha1", "md5", "adler32"},
 			PreferredUploadType: "",

services/frontend/pkg/revaconfig/config.go

@@ -165,7 +165,7 @@ func FrontendConfigFromStruct(cfg *config.Config) map[string]interface{} {
 								"share_with_group_members_only":     true,
 								"share_with_membership_groups_only": true,
 								"default_permissions":               22,
-								"search_min_length":                 3,
+								"search_min_length":                 cfg.SearchMinLength,
 								"public": map[string]interface{}{
 									"alias":                      true,
 									"enabled":                    true,