lava-expect: enable LAVA expect support

This is the first patch of a series to enable 'expect' in the Open CI
framework [1]. Under the Open CI enviroment, the expect support is done
in LAVA and not using `expect` tool, through LAVA Interactive Actions
[2], where expect strings are transformed into one or more LAVA
Interactive Actions, matching either successes or failures
strings. All dynamically created LAVA content is finally located in
the LAVA job definition, where ultimatelly, LAVA matches the
corresponding strings.

[1] https://projects.linaro.org/browse/TFC-36
[2] https://validation.linaro.org/static/docs/v2/actions-test.html?highlight=interactive#interactive-test-action

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: Iff454bd3714a38a729022a98a862ea08e8f440fc
4 files changed