Improve: Add more API tests

[r0zbot]

Proposed changes (including videos or screenshots)

Add end-to-end tests for untested endpoints.

Issue(s)

Steps to test or reproduce

Further comments

Tested endpoints:

• /api/v1/push.token
• /api/v1/im.messages.others
• /api/v1/im.files
• /api/v1/findOrCreateInvite
• /api/v1/listInvites
• /api/v1/removeInvite
• /api/v1/useInviteToken
• /api/v1/validateInviteToken
• /api/v1/chat.unStarMessage
• /api/v1/chat.ignoreUser
• /api/v1/groups.online
• /api/v1/groups.members
• /api/v1/groups.listAll
• /api/v1/groups.files
• /api/v1/channels.online
• /api/v1/channels.join
• /api/v1/channels.files
• /api/v1/users.resetAvatar
• /api/v1/users.getAvatar
• /api/v1/users.deactivateIdle
• /api/v1/shield.svg

[CLAassistant]

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