cmd: add a fetch utility

cmd: add a fetch utility

Add a small utility for displaying some information about U-Boot and the
hardware it's running on in a similar fashion to the popular neofetch
tool for Linux [1].

While the output is meant to be useful, it should also be pleasing to
look at and perhaps entertaining. The ufetch command aims to bring this
to U-Boot, featuring a colorful ASCII art version of the U-Boot logo.

[1]: https://en.wikipedia.org/wiki/Neofetch

Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # vim3
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8560-QRD
Acked-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Tested-by: Tony Dinh <mibodhi@gmail.com>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>