feat!: incorporates ParitySharesNamespace and TailPaddingNamespace in…

…to IsReserved function (#2194)

## Overview
Closes #celestiaorg/celestia-app#2138
This PR also addresses the concerns raised in the
[comment](celestiaorg/celestia-app#2138 (comment))
by introducing a distinction between two types of reserved namespaces.
Namespaces within the range [0-255] are now identified as "Primary
Reserved Namespaces," while any other reserved namespaces beyond this
range are categorized as "Non-Primary Reserved Namespaces." Hopefully,
this differentiation provides better clarity and organization regarding
namespace allocation and usage within the code.

## Checklist

- [x] New and updated code has appropriate documentation
- [x] New and updated code has new and/or updated testing
- [x] Required CI checks are passing
- [x] Visual proof for any user facing features like CLI or
documentation updates
- [x] Linked issues closed with keywords

pkg/namespace/consts.go

@@ -51,9 +51,10 @@ var (
 	// (ordinary and PFBs) but before blobs.
 	ReservedPaddingNamespace = MustNewV0([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 255})
 
-	// MaxReservedNamespace is lexicographically the largest namespace that is
-	// reserved for protocol use.
-	MaxReservedNamespace = MustNewV0([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 255})
+	// MaxPrimaryReservedNamespace represents the largest primary reserved
+	// namespace reserved for protocol use. Note that there may be other
+	// non-primary reserved namespaces beyond this upper limit.
+	MaxPrimaryReservedNamespace = MustNewV0([]byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 255})
 
 	// TailPaddingNamespace is the namespace reserved for tail padding. All data
 	// with this namespace will be ignored.

pkg/namespace/namespace.go

@@ -104,8 +104,12 @@ func validateID(version uint8, id []byte) error {
 	return nil
 }
 
+// IsReserved returns true if the namespace is reserved for protocol-use.
 func (n Namespace) IsReserved() bool {
-	return bytes.Compare(n.Bytes(), MaxReservedNamespace.Bytes()) < 1
+	isLessThanOrEqualToMaxPrimaryReservedNamespace := bytes.Compare(n.Bytes(), MaxPrimaryReservedNamespace.Bytes()) < 1
+	isParityNamespace := n.IsParityShares()
+	isTailPadding := n.IsTailPadding()
+	return isLessThanOrEqualToMaxPrimaryReservedNamespace || isParityNamespace || isTailPadding
 }
 
 func (n Namespace) IsParityShares() bool {

pkg/namespace/random_blob.go

@@ -43,14 +43,6 @@ func isBlobNamespace(ns Namespace) bool {
 		return false
 	}
 
-	if ns.IsParityShares() {
-		return false
-	}
-
-	if ns.IsTailPadding() {
-		return false
-	}
-
 	if !slices.Contains(SupportedBlobNamespaceVersions, ns.Version) {
 		return false
 	}