[new feature] Card: add click-thumb event (youzan#3586)

[new feature] Card: add click-thumb event (youzan#3585)

[bugfix] Image: missing type definition (youzan#3520)

[changelog] 2.0.0

[new feature] ActionSheet: add click-overlay event

[bugfix] Switch: incorrect activeColor when use activeValue

[improvement] Uploader: optimize code

[bugfix] Icon: should support render local image

Merge branch 'dev' of https://github.com/youzan/vant into dev

[new feature] Card: add bottom slot