improve promises examples

create async/await examples for:
- addItem
- changeActiveEntities
- deleteItem
- getActiveEntities
- getActiveProfile
- getAllItems
- getAnItem
- getFullSession
- getMyEntities
- getMyProfiles
- getSubItems
- initSessionByCredentials
- initSessionByUserToken
- killSession
- passwordReset
- updateItem
- resetPasswordRequest
- getGlpiConfig