fst-manager: initial HAL support

Initial support for HAL interface in order to control
the fst-manager from WIFI framework.
This includes infrastructure to start the HAL when
fst-manager is started, and using the fst-manager
event loop (eloop) to service HAL requests.
Also includes .rc file in order to start the fst-manager
with support for lazy HAL mechanism. These definitions
will be removed from init.qcom.rc by a separate patch.
In addition, support the following new features:
- dynamic enslave of master interface
- rename group interfaces at runtime
- rename group MUX interface at runtime
- report whether FST and WIFI SON modes are supported.

For supporting dynamic configuration change such
as interfaces names, implement cached runtime config
for the INI file. Instead of reading the INI file
again for each query, cache the INI contents once
when initializing, and all queries are returned from
the cache. This makes it easy to update the
information, because only the cache needs updating.

The methods for renaming MUX interface and group
interfaces are stubs, and will be implemented in
next patch.

Change-Id: I5af23bf00509a944f2b6ca07a047804003d54fe1