[MM-28422] Enable processing of import files through API (#16062)

* Implement unzip function

* Implement FileSize method

* Implement path rewriting for bulk import

* Small improvements

* Add ImportSettings to config

* Implement ListImports API endpoint

* Enable uploading import files

* Implement import process job

* Add missing license headers

* Address reviews

* Make path sanitization a bit smarter

* Clean path before calculating Dir

* [MM-30008] Add mmctl support for file imports (#16301)

* Add mmctl support for import files

* Improve test

* Remove unnecessary handlers

* Use th.TestForSystemAdminAndLocal

* Make nouser id a constant

model/config_test.go

@@ -1389,3 +1389,31 @@ func TestSetDefaultFeatureFlagBehaviour(t *testing.T) {
 	require.Equal(t, "somevalue", cfg.FeatureFlags.TestFeature)
 
 }
+
+func TestConfigImportSettingsDefaults(t *testing.T) {
+	cfg := Config{}
+	cfg.SetDefaults()
+
+	require.Equal(t, "./import", *cfg.ImportSettings.Directory)
+	require.Equal(t, 30, *cfg.ImportSettings.RetentionDays)
+}
+
+func TestConfigImportSettingsIsValid(t *testing.T) {
+	cfg := Config{}
+	cfg.SetDefaults()
+
+	err := cfg.ImportSettings.isValid()
+	require.Nil(t, err)
+
+	*cfg.ImportSettings.Directory = ""
+	err = cfg.ImportSettings.isValid()
+	require.NotNil(t, err)
+	require.Equal(t, "model.config.is_valid.import.directory.app_error", err.Id)
+
+	cfg.SetDefaults()
+
+	*cfg.ImportSettings.RetentionDays = 0
+	err = cfg.ImportSettings.isValid()
+	require.NotNil(t, err)
+	require.Equal(t, "model.config.is_valid.import.retention_days_too_low.app_error", err.Id)
+}