fix(Markdown): render markdown in more secure way

This commit changes markdown sanitization behaviour in following way:

class, style and data-* attributes are removed by default. These attributes
open possible vulnerability vectors to attackers.

The original behavior of sanitizer (before this commit) can be enabled by *useUnsafeMarkdown* configuration option.
Use this configuration option with caution and only in cases when you know
what you're doing.

src/core/components/auth/oauth2.jsx

@@ -109,7 +109,7 @@ export default class Oauth2 extends React.Component {
     const Button = getComponent("Button")
     const AuthError = getComponent("authError")
     const JumpToPath = getComponent("JumpToPath", true)
-    const Markdown = getComponent( "Markdown" )
+    const Markdown = getComponent("Markdown", true)
     const InitializedInput = getComponent("InitializedInput")
 
     const { isOAS3 } = specSelectors