Wifi: support multiple WIFI chips

The WIFI HAL API has support for multiple WIFI chips
(IWifiChip instances) however the implementation
is hard-coded to support only a single WIFI chip.
This change reworks the implementation so multiple
WIFI chips will be supported.
Support for multiple chips is based on the concept
that each chip is represented by its own vendor HAL
library.
The implementation will look for descriptor
files for vendor HAL libraries under
/vendor/etc/wifi/vendor_hals. It will parse
descriptors, dynamically load vendor HAL libraries
and create WifiLegacyHal and WifiChip objects for
each loaded vendor HAL library.
One of the descriptors should be marked with "primary"
flag. The implementation will create the first WifiChip
object for this library. Typically it is the one
providing the best WIFI functionality, which was
previously used as the only WIFI chip.
Additional support is added inside WifiChip and
WifiLegacyHal for getting available chip modes
and concurrency combinations from the vendor HAL
if available, and allowing the chip to override
network interface name when creating interfaces.
The mechanism for getting chip capabilities is
improved to allow getting chip-global capabilities,
which are independent of any created interfaces.
For example, if the framework needs to start
a SoftAP on the 60GHz band, it needs to find a
chip which supports this band, but before creating
any interface on the chip. The new mechanism allows
this.

Bug: 146922967
Test: atest VtsHalWifiV1_0TargetTest VtsHalWifiNanV1_0TargetTest VtsHalWifiApV1_0TargetTest \
            VtsHalWifiV1_1TargetTest \
            VtsHalWifiV1_2TargetTest VtsHalWifiNanV1_2TargetTest \
            VtsHalWifiV1_3TargetTest \
            VtsHalWifiApV1_4TargetTest VtsHalWifiNanV1_4TargetTest VtsHalWifiRttV1_4TargetTest
Change-Id: Ibdff93ea56aff186d4b5361ac77f6f448a0dfd45