emulator: Add initial support for MSFT vendor commands

emulator: Add initial support for MSFT vendor commands

This adds the initial support for MSFT vendor commands and enable them
when in btvirt:

< HCI Command: Microsoft Ex.. (0x3f|0x001e) plen 1
      Read Supported Features (0x00)
> HCI Event: Command Complete (0x0e) plen 14
      Microsoft Extension (0x3f|0x001e) ncmd 1
      Read Supported Features (0x00)
        Status: Success (0x00)
        Features: 0x3f 0x00 0x00 0x00 0x00 0x00 0x00 0x00
          RSSI Monitoring feature for BR/EDR
          RSSI Monitoring feature for LE connections
          RSSI Monitoring of LE advertisements
          Advertising Monitoring of LE advertisements
          Verifying the validity of P-192 and P-256 keys
          Continuous Advertising Monitoring
        Event prefix length: 0
        Event prefix:
< HCI Command: Microsoft Ex.. (0x3f|0x001e) plen 2
      LE Set Advertisement Filter Enable (0x05)
        Enable: All filter conditions (0x01)
> HCI Event: Command Complete (0x0e) plen 5
      Microsoft Extension (0x3f|0x001e) ncmd 1
      LE Set Advertisement Filter Enable (0x05)
        Status: Success (0x00)

Signed-off-by: Anuj Jain <anuj01.jain@samsung.com>
Signed-off-by: Ayush Garg <ayush.garg@samsung.com>