docs: add THIRD-PARTY-LICENSES file

THIRD-PARTY-LICENSES is built using an internal tool to organize the attribution for the SDK. Additionally, it also allows to keep track of the dependency versions.

Also update PR template to make when a change is made, THIRD-PARTY-LICENSES is kept up to date.

Author: Ganesh Jangir

.github/pull_request_template.md

@@ -6,6 +6,10 @@
 ## Description of changes
 <!--- Why is this change required? What problem does it solve? -->
 
+## New/existing dependencies impact assessment, if applicable
+<!--- No new dependencies were added to this change. -->
+<!--- If any dependency was added / modified / removed, THIRD-PARTY-LICENSES must be updated accordingly. -->
+
 ## Conventional Commits
 <!--- Please use conventional commits to let us know what kind of change this is.-->
 <!--- More info can be found here: https://www.conventionalcommits.org/en/v1.0.0/-->