Merge uart_terminal from https://github.com/xMasterX/all-the-plugins

uart_terminal/README-catalog.md

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+The UART Terminal application allows you to use UART (Universal Asynchronous Receiver-Transmitter) even without a computer, only with your Flipper Zero:
+
+1. On your Flipper Zero, run the UART Terminal app.
+2. Connect your Flipper Zero to a device that uses the UART  protocol for communication.
+3. Select the desired communication frequency. After that, you can start reading and writing data directly from the application.