Revert "build: Bump D-Bus dependency to 1.6"

This reverts commit 325c0a39bb9e40fadca4fe545b28d5ae3536919d.
Revert "tools/bluetooth-player: check path validity"

This reverts commit 1d7c6a807d1d81e43110bae466f8e34cbffb088c.
attrib/gatt: Minor fix code style
shared/gatt: Extract send_att function

This function sends already prepared buffer. We need this helper
function in following patch
shared/gatt: Add bt_send_att_with_id functions

In case of char or descriptors search it might happen we have to send
couple of att commands and it is done under the hood.
In the same time used doing char discovery or descriptor search has
request id from the first ATT command, which means client gets outdated
if there is more command send. That means that client is not able to
e.g. cancle ongoing search if he would like to do it.
attrib/gattrib: Fix gattrib send command

If client provides id to the g_attrib_send function it should be taken
into account and appropriate bt_att_send* should be called
attrib/gatt: Fix for search searvices

This patch adds means to reuse att request id for GATT operations
which might need more then one ATT req for complete reguest. Meaning
discover primary\included services and discover
characteristics/descriptors

This is needed for user of gattib, to make sure that att request id he
holds is valid during whole gatt operation.

So far, it could happen that gattrib did additional ATT request without
user knowledge which leads to situation that user had outdated att
request id.

Note that request id is used by the user for canceling request.
android/bluetooth: Minor typo fix
android/bluetooth: Minor fix, add missing NULL assignment
android/gatt: Fix for setting conn timeout
android/hog: Minor coding style fixes
android/bluetooth: Add possibility to register for bonded event

Some modules might be interested in fact that device has been bonded.
This patch allows to register for that event

Note that callback is called only on success bonding.
android/gatt: Add paired cb to gatt.c

This will be required in order to register for Service Changed on remote
device
android/bluetooth: Add API to check if device is bonding

Some modules like GATT might be interested in information about ongoing
bonding on device. It can be useful e.g. to take decision if GATT can do
service search or should wait until bonding is done.
android/gatt: Improve LE connection after pair

With this patch, GATT keeps ATT connection for 30 sec during bonding,
and once bonding is completed GATT starts service search.

It is needed for example when user choose HOG device from Settings
Application. So far scenario looks like that:

1. Bonding started
2. GATT Service search
3. Bonding ended and LE connection dropped
4. Initiated connection to HOG device

Now it looks like that:

1. Bonding Started
2. Bonding Ended
3. GATT Search Service
4. Connect to HOG device on existing LE connection
android/hog: Add support to track gatt operations
android/hog: Cancel all GATT operations on disconnect

This patch makes sure that HOG cancels its GATT requests before
removing his attrib reference.

However some request might not be possible to cancel. It will be handled
in following patches
android/hog: Keep track on primary and include service search
android/hog: Keep track on discover characteristic and descriptors
android/hog: Keep track on read/write char and descr