parser: Add GPIO query engine

This new query engine handles the new 'gpio' CAmkES queries that the new
seL4GPIOServer connector exposes for its access control mechanisms.

The engine takes in a YAML file containing a list of GPIO pins and sorts
out the 'gpio' queries so that the connector templates for the
seL4GPIOServer connector can generate the appropriate structures and
functions.

parser: move DTBMatchQuery to FDTQueryEngine

camkes/parser: add query to camkes ADL

This commit adds a new feature called a query. A query appears in the
ADL on the RHS of a setting in the configuration section of the ADL, eg:

configuration {
component.blah = query()
}

queries takes comma separated parameters that can be any literal (numeric_expr |
multi_string | list | dict).

Queries are parsed in a new parsing stage between stage7 and stage8.

Fix licenses

Refactored parser init commit.

Release snapshot