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.

parser: allow for dict lookups in attribute references

This commit adds the ability to look up values in attribute references
that are dictionaries.

The syntax is the same as python dict lookups and is as follows:

s.bah <- y.attribute['key']['anotherkey']

Fix licenses

CAMKES-584: Add Struct type to camkes

Struct type represents a collection of attributes. Attributes are set by
providing a dictionary of fields and values

Added binary_semaphore primitive

Refactored parser init commit.

Remove AST type `Direction`.

This AST object was not gaining us anything as you always needed to look at its
content to do anything with it. In the templates it was inducing strange code
of the form `p.direction.direction`. This commit removes the type entirely. RPC
parameter directions are now represented as bare strings.

This also relevant in movement towards JIRA CAMKES-334.

Merge all AST objects into a single file.

There is no longer any meaningful distinction between CAmkES ADL and IDL and
the separation into two distinct collections of AST objects is no longer
relevant. Having the two objects in separate locations was leading to confusion
and preventing some desirable refactoring in this area.

JIRA CAMKES-334

Release snapshot