[#1] Add frostfs backend

Signed-off-by: Aleksey Kravchenko <al.kravchenko@yadro.com>

internal/backend/frostfs/config_test.go

@@ -0,0 +1,28 @@
+package frostfs
+
+import "testing"
+
+func TestParseConfig(t *testing.T) {
+	for i, test := range []struct {
+		s   string
+		cfg Config
+	}{
+		{"frostfs:grpcs://s01.frostfs.devenv:8080/container-name", Config{
+			Endpoint:    "grpcs://s01.frostfs.devenv:8080",
+			Container:   "container-name",
+			Connections: 5,
+		}},
+	} {
+		cfg, err := ParseConfig(test.s)
+		if err != nil {
+			t.Errorf("test %d:%s failed: %v", i, test.s, err)
+			continue
+		}
+
+		if *cfg != test.cfg {
+			t.Errorf("test %d:\ninput:\n  %s\n wrong config, want:\n  %v\ngot:\n  %v",
+				i, test.s, test.cfg, cfg)
+			continue
+		}
+	}
+}