feat(weex): implement "weex.supports" api to support feature detection

[Hanks10100]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes
• No

Other information:

weex.supports

weex.supports is used to detect whether a feature is supported in the current environment.

API

weex.supports(condition: String): Boolean | Null

Parameter

• a formatted string: @{type}/{name}.

The type must be "component" or "module", the name can be tag name, module name or the method name in a specific module.

Return Value

• if supported, returns true.
• if unsupported, returns false.
• if unclear, returns null.

Examples

// Detects whether the specific component is supported
weex.supports('@component/slider') // true
weex.supports('@component/my-tab') // false

// Detects whether the specific module is supported
weex.supports('@module/stream')  // true
weex.supports('@module/abcdef')  // false

// Detects whether the method in specific module is supported
weex.supports('@module/dom.getComponentRect') // true
weex.supports('@module/navigator.jumpToPage') // false

// invalid input
weex.supports('div') // null
weex.supports('module/*') // null
weex.supports('@stream/fetch') // null
weex.supports('getComponentRect') // null