Support viewing SWO data

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Configuration

Operating system: Win 10 x64

PlatformIO Version (platformio --version): version 5.2.1b2

Description of problem

Per https://community.platformio.org/t/viewing-swo-output-within-pio/13853.

PlatformIO currently has no built-in facilities to view printf() output sent via the SWO (single-wire-output) pin present in many ARM-type microcontrollers.

SWO (using the "SWO" pin) is a different technique to SWD semihosting (uses SWDIO + SWDCLK pins), thus this issue is not a duplicate of #3516 .

Steps to Reproduce

1. Create firmware that uses the SWO output (e.g., STM32Cube firmware using the ITM_SendChar() function to send data)
2. Upload firmware
3. View SWO output normally via the e.g. ST-Link Utility

4. Search for the option to view SWO output within PlatformIO (e.g., via "Monitor" task)

Actual Results

The "Monitor" task cannot be configured to view SWO output. No other button for "show me SWO output" exists.

Expected Results

PlatformIO is capable of viewing SWO output out-of-the-box.

If problems with PlatformIO Build System:

N/A

Additional info

By using OpenOCD to read SWO output and forward it to a TCL server (it cannot output it in stdout by default) and using a SWO decoder script (https://github.com/robertlong13/SWO-Parser) that connects to OpenOCD's TCL server, one can view the SWO output.

The repo https://github.com/maxgerhardt/pio-swo-demo demonstratess that and implements a "SWO Viewer" task that acts like a serial monitior, just for SWO data.

Start by reviewing the linked pio-swo-demo, SWO-Parser, and the OpenOCD/TCL-server approach described in the issue. Then locate PlatformIO's Monitor task and determine how SWO data could be viewed within PlatformIO. Done means PlatformIO can view SWO output out-of-the-box, with the required workflow and supported configuration defined.