Version transaction message and add new message format (#18725)

* Version transaction message and add new message format

* Update abi digest due to message path change

* Update v0.rs

Fix comment

* Update original.rs

* Update message versions name and address map indexes field name

* s/original/legacy

* update comment

* cargo fmt

* Update abi digest due to legacy rename

sdk/program/src/message/mod.rs

@@ -0,0 +1,27 @@
+//! A library for generating a message from a sequence of instructions
+
+mod legacy;
+mod v0;
+mod versions;
+
+pub use legacy::Message;
+
+pub const MESSAGE_HEADER_LENGTH: usize = 3;
+
+#[derive(Serialize, Deserialize, Default, Debug, PartialEq, Eq, Clone, AbiExample)]
+#[serde(rename_all = "camelCase")]
+pub struct MessageHeader {
+    /// The number of signatures required for this message to be considered valid. The
+    /// signatures must match the first `num_required_signatures` of `account_keys`.
+    /// NOTE: Serialization-related changes must be paired with the direct read at sigverify.
+    pub num_required_signatures: u8,
+
+    /// The last num_readonly_signed_accounts of the signed keys are read-only accounts. Programs
+    /// may process multiple transactions that load read-only accounts within a single PoH entry,
+    /// but are not permitted to credit or debit lamports or modify account data. Transactions
+    /// targeting the same read-write account are evaluated sequentially.
+    pub num_readonly_signed_accounts: u8,
+
+    /// The last num_readonly_unsigned_accounts of the unsigned keys are read-only accounts.
+    pub num_readonly_unsigned_accounts: u8,
+}