fix(people): correct friends list API endpoints and contract version

[misiektoja]

Hi, I switched my project from xbox-webapi-python to python-xbox and noticed that my code for fetching the list of friends was not working anymore.

It turned out the get_friends_by_xuid() method was not working correctly:

1. It had a broken URL path /users/me/people/xuids({xuid})/... which returns the authenticated user's info, not the target user's friends list. The correct path is /users/xuid({xuid})/people/social/...

2. Contract version 7 returns empty results for get_friends_by_xuid(). When querying another user's friends list, contract v7 returns {"people": []} while v5 returns the actual friends list.

I compared behavior across contract versions:

Version	get_friends_own	get_friends_by_xuid
v3 (original xbox-webapi)	OK	OK
v5	OK	OK
v7	OK	NOT OK

I noticed contract v7 was introduced in PR #1 to provide additional relationship fields (isFriend, canBeFriended etc.). However, these fields are only returned when querying your OWN friends list - get_friends_by_xuid() returns empty with v7 when querying another user.

I implemented usage of different contract versions per method to get the best of both worlds:

Method	Contract Version	Reason
get_friends_own	v7	Full relationship fields
get_friends_by_xuid	v5	v7 returns empty for other users