tools: generalise jinja_lint support to non-CAmkES use cases

This change makes the Jinja linter capable of understanding templates that don't
use the same start and end markers as CAmkES does. In particular, it makes the
default markers the Jinja defaults ('{%' and friends) and allows controlling
this via command line options.

Signed-off-by: Matthew Fernandez <matthew.fernandez@gmail.com>

Fix licenses

Refactored parser init commit.