Tockloader

This release improves Tockloader support on Windows.

Other improvements:
- Autodiscover the nrf52840dk on openocd.
- ShortId TBF header.
- Autodiscover the VCOM0 port on the nrf52840dk for `tockloader listen`.

- Improve command line help
- Update STM boards
- Add requirements.txt
- Use nrf52840 for jlink rather than nrf52

Changes in this release:
- Support reading kernel attributes to detect where application RAM starts.
- Skip sending empty pages in the serial bootloader connection.
- Update menus for interactive options.
- Better understand app RAM addresses when installing fixed address apps.

This release includes general improvements to Tockloader. The two main changes are:

- Add support for credentials. There is a new command `tockloader tbf credential` which allows for creating, viewing, verifying, and removing credentials for a TAB.
- Add support for TicKV. Tockloader can now query a tickv key-value store, and add/remove objects.

In this release:

- Added SMA Q3 and QEMU RISC-V 32 bit "virt" boards
- OpenOCD fixes and updates
- Added `Display` class for doing machine readable output in JSON format
- Added interactive selection menu instead of having to enter a number to choose the architecture to inspect

The main improvement of this release of Tockloader is board-specific operations are now more clearly separated between configurations that impact how applications are organized and installed on the board, and configurations that impact how Tockloader communicates with the board. The former are in tockloader.py, while the latter are in board_interface.py.

Other updates:
- There is a new `--flash-file` option that allows writing apps to a local file.
- There are new `tbf-X` commands that enable manipulating local TAB files.
- There is support for the new kernel version TLV.
- Uninstall now replaces removed apps with a padding app.
- Minimum app sizes are no longer needed as tockloader respects writing entire flash pages.