Update documentation for how to write tests and the 'ut' command.

Signed-off-by: Simon Glass <sjg@chromium.org>

Update documentation for the 'ut' command, since it has changed a
little.

Signed-off-by: Simon Glass <sjg@chromium.org>

The UT_TESTF_ macros read as 'unit test test flags' which is not right.
Rename to UTF ('unit test flags').

This has the benefit of being shorter, which helps keep UNIT_TEST()
declarations on a single line.

Give the enum a name and reference it from the UNIT_TEST() macros while
we are here.

Signed-off-by: Simon Glass <sjg@chromium.org>

%s/Synopis/Synopsis/g

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

Add the description of CLI commands to the generated index.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>

When running unit tests, some may have side effects which cause a
subsequent test to break. This can sometimes be seen when using 'ut dm'
or similar.

Add a new argument which allows a particular (failing) test to be run
immediately after a certain number of tests have run. This allows the
test causing the failure to be determined.

Update the documentation also.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a 'ut info' command to show the number of suites and tests. This is
useful to get a feel for the scale of the tests.

Signed-off-by: Simon Glass <sjg@chromium.org>

Before adding more options, document this command.

Signed-off-by: Simon Glass <sjg@chromium.org>