spl: adding metadata account type

spl/src/metadata.rs

@@ -183,3 +183,31 @@ pub struct MintNewEditionFromMasterEditionViaToken<'info> {
     //
     pub metadata_mint: AccountInfo<'info>,
 }
+
+#[derive(Clone, Debug, PartialEq)]
+pub struct MetadataAccount(mpl_token_metadata::state::Metadata);
+
+impl MetadataAccount {
+    pub const LEN: usize = mpl_token_metadata::state::MAX_METADATA_LEN;
+}
+
+impl anchor_lang::AccountDeserialize for MetadataAccount {
+    fn try_deserialize_unchecked(buf: &mut &[u8]) -> anchor_lang::Result<Self> {
+        meta_deser(buf).map(MetadataAccount).map_err(Into::into)
+    }
+}
+
+impl anchor_lang::AccountSerialize for MetadataAccount {}
+
+impl anchor_lang::Owner for MetadataAccount {
+    fn owner() -> Pubkey {
+        ID
+    }
+}
+
+impl Deref for MetadataAccount {
+    type Target = mpl_token_metadata::state::Metadata;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}