SDK-3337: parse clientId from ID Token `azp` claim

[garciafdezpatricia]

This PR fixes clientId not being parsed from the token payload.

• [x] I've added a unit test to test for potential regressions of this bug.
• [x] The changelog has been updated, if applicable.
• [x] Commits in this PR are minimal and have descriptive commit messages.

[NSeydoux]

And don't forget to add a CHANGELOG.md entry describing this fix and how it impacts library users.

[NSeydoux]

I'll let you write the commit message. The current PR title looks good for a commit title.