[#1523] neofs-node: Refactor configuration

1. Move compression parameters to the `shard` section.
2. Allow to use multiple sub-storage components in the blobstor.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>

cmd/neofs-node/config/engine/shard/blobstor/storage/config.go

@@ -0,0 +1,55 @@
+package storage
+
+import (
+	"io/fs"
+
+	"github.com/nspcc-dev/neofs-node/cmd/neofs-node/config"
+)
+
+type Config config.Config
+
+// PermDefault are default permission bits for BlobStor data.
+const PermDefault = 0660
+
+func From(x *config.Config) *Config {
+	return (*Config)(x)
+}
+
+// Type returns storage type.
+func (x *Config) Type() string {
+	return config.String(
+		(*config.Config)(x),
+		"type")
+}
+
+// Path returns the value of "path" config parameter.
+//
+// Panics if the value is not a non-empty string.
+func (x *Config) Path() string {
+	p := config.String(
+		(*config.Config)(x),
+		"path",
+	)
+
+	if p == "" {
+		panic("blobstor path not set")
+	}
+
+	return p
+}
+
+// Perm returns the value of "perm" config parameter as a fs.FileMode.
+//
+// Returns PermDefault if the value is not a non-zero number.
+func (x *Config) Perm() fs.FileMode {
+	p := config.UintSafe(
+		(*config.Config)(x),
+		"perm",
+	)
+
+	if p == 0 {
+		p = PermDefault
+	}
+
+	return fs.FileMode(p)
+}