Split out BindingRuntimeGenerator

Split out BindingRuntimeGenerator

BindingRuntimeContext does not require all of the information
captured in a normal BindingGenerator run, such as constants, comments
and similar.

The fact that we do not have separation between compile-time and
run-time granularity of this data comes from history of the codebase,
when BindingRuntimeContext did not exist in its current form and we
infered much of the information from the classes lazily.

Introduce BindingRuntimeGenerator interface and refactor
BindingGeneratorImpl to reflect this split. This leads to faster
BindingRuntimeContext creation, as the call to generateTypes()
is no longer needed.

JIRA: MDSAL-312
Change-Id: Ibb1c22d4e4c9ff90e37d6e10e258f632a9c87ef5
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>