Add bold/html support in resultCard

[guojiex]

htmlTitle and htmlSnippet are provided by Custom Search JSON API. but now we just use the plain text returned.

[guojiex]

https://stackoverflow.com/questions/41557139/how-do-i-bold-or-format-a-piece-of-text-within-a-paragraph

Use RichText with a list of TextSpan. can render this. But not sure how to parse the html to textspans.

[guojiex]

Or try to use https://gist.github.com/Katarn/588725dce850c81da8a551f92fb0923a

[guojiex]

Or we can use platform specific webView

https://developer.android.com/reference/android/webkit/WebView

https://developer.apple.com/documentation/webkit/wkwebview