And add rule "no-var" to eslintrc

Use eslint rule to check the diff between var and let:
    "no-use-before-define": "off"
    "@typescript-eslint/no-use-before-define": 2
    no-redeclare: 2
    block-scoped-var: 2
    no-loop-func: 2
(2) By the way add some eslint rule and unify some code style.

* fix bug #9563

* Modify clerical error

#8132

if angle is smaller than minAngle, label does not show

#7614

fix and close #7575

Interpolation method is not supported for gradient, so animation is disabled when color is gradient.

Fix and close #7569