fix: remove the player view when destroy player

[passerbyloo]

Description of the Changes

when call player.destroy().
the player view still not remove/release, like

player.destroy()
player = PlayKitManager.sharedInstance.loadPlayer(config: config)
playerView = PlayerView.createPlayerViewForPlayer(player)

if play the same video source in two player, the video can not play normally.

CheckLists

• changes have been done against master branch, and PR does not conflict
• new unit / functional tests have been added (whenever applicable)
• test are passing in local environment
• Travis tests are passing (or test results are not worse than on master branch :))
• Docs have been updated