add UpdateLiffView for liff.yml

[odanado]

In LiffView, view.url and view.type are required properties. However, in the LIFF app update API, these properties are not mandatory. ref: https://developers.line.biz/en/reference/liff-server/#update-liff-app

I have defined a new UpdateLiffView to solve this issue.

[CLAassistant]

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