refactor(app): Added solana send txn support

apps/solana_app/solana_main.c

@@ -127,6 +127,10 @@ void solana_main(usb_event_t usb_evt, const void *app_config) {
       solana_get_pub_keys(&query);
       break;
     }
+    case SOLANA_QUERY_SIGN_TXN_TAG: {
+      solana_sign_transaction(&query);
+      break;
+    }
 
     default: {
       /* In case we ever encounter invalid query, convey to the host app */

apps/solana_app/solana_priv.h

@@ -17,6 +17,24 @@
 #include <stdint.h>
 
 #include "solana_context.h"
+#include "solana_txn_helpers.h"
+
+/*****************************************************************************
+ * TYPEDEFS
+ *****************************************************************************/
+
+typedef struct {
+  /**
+   * The structure holds the wallet information of the transaction.
+   * @note Populated by solana_handle_initiate_query()
+   */
+  solana_sign_txn_initiate_request_t init_info;
+
+  /// remembers the allocated buffer for holding complete unsigned transaction
+  uint8_t *transaction;
+  /// store for decoded unsigned transaction info
+  solana_unsigned_txn transaction_info;
+} solana_txn_context_t;
 
 /**
  * @brief Handler for SOLANA public key derivation.
@@ -27,4 +45,14 @@
  */
 void solana_get_pub_keys(solana_query_t *query);
 
+/**
+ * @brief Handler for signing a transaction on Solana.
+ * @details The expected request type is SOLANA_SIGN_TXN_REQUEST_INITIATE_TAG.
+ * The function controls the complete data exchange with host, user prompts and
+ * confirmations for signing an Solana based transaction.
+ *
+ * @param query Reference to the decoded query struct from the host app
+ */
+void solana_sign_transaction(solana_query_t *query);
+
 #endif /* SOLANA_PRIV_H */