bootstd: Add tests for bootstd including all uclasses

Add a set of combined tests for the bootdev, bootflow and bootmeth
commands, along with associated functionality.

Expand the sandbox console-recording limit so that these can work.

These tests rely on a filesystem script which is not yet added to the
Python tests. It is included here as a shell script.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index 77a3408..963ec91 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -708,6 +708,7 @@
 F:	include/bootmeth.h
 F:	include/bootstd.h
 F:	net/eth_bootdevice.c
+F:	test/boot/
 
 BTRFS
 M:	Marek Behun <marek.behun@nic.cz>