Mesh: Apply Fixes & code refactoring

Mesh: Apply Fixes & code refactoring

This patch handles following.
1. Few Fixes(some of them are mentioned below)
2. Enable DEBUG logs across all layers
3. Minor code refactoring & indentations
3. Review comments from 'ble_mesh' dev branch
   3.1. Dont Free user data from request info
     [Patch: 237446]
   3.2. Fix typo's for following commits
     [Patch: 237447, 237445, 237440, 237435]

Some of the notable fixes applied are following:-
1. Fix bt-service crash during cleanup of mesh framework resources
   [Resolution: removing double free of Mesh model resources]
2. Fix crash in unit test app during Scan stop operation
   [Resolution: Dont allow Stop scan if scanning is not in progress]
3. Fix Node Browse event fail issue
   [Resolution: Handle wrong usage of event pointer]
4. Fix "Timer expired even if response is received within timeout" issue.
   [Resolution: Remove timer once event is received from stack]
5. Fix "TTL configured callback(CAPI callback)" is not invoked in case of success
   Resolution: Handle wrong usage of event pointer in service layer]
6. Fix NetKey configuration API failed due to mishandling of Key in Network
   [Resolution: Network Key handling is corrected]

Change-Id: I47d3b93c19650dea039ecdf0b8862be32d8d3a96
Signed-off-by: Anupam Roy <anupam.r@samsung.com>