[generator] Fix parameter string in ref doc links

[pjcollins]

Fixes: #931
Fixes: #932

We have a handful of issues in the https://developer.android.com/ links
that are generated for various type members with complex parameters.
Collections, varargs, and generics are some examples of items that are
not translated correctly when generating the parameter portion of the
reference documentation URL.

The javadoc that we generate for Mono.Android contains <parameter/>
elements under all relevant methods. These elements contain attributes
with additional type data; for instance:

    <method jni-return="Landroid/animation/ObjectAnimator;" jni-signature="(Ljava/lang/Object;Landroid/util/Property;Landroid/util/Property;Landroid/graphics/Path;)Landroid/animation/ObjectAnimator;" name="ofFloat" return="android.animation.ObjectAnimator">
      <parameter jni-type="Ljava/lang/Object;" name="target" type="T"/>
      <parameter jni-type="Landroid/util/Property;" name="xProperty" type="android.util.Property&lt;T, java.lang.Float&gt;"/>
      <parameter jni-type="Landroid/util/Property;" name="yProperty" type="android.util.Property&lt;T, java.lang.Float&gt;"/>
      <parameter jni-type="Landroid/graphics/Path;" name="path" type="android.graphics.Path"/>
      <javadoc>
        <![CDATA[Constructs and returns an ObjectAnimator that animates coordinates along a <code>Path</code>
    using two properties. A <code>Path</code></> animation moves in two dimensions, animating
    coordinates <code>(x, y)</code> together to follow the line. In this variation, the
    coordinates are floats that are set to separate properties, <code>xProperty</code> and
    <code>yProperty</code>.

    @param target The object whose properties are to be animated.
    @param xProperty The property for the x coordinate being animated.
    @param yProperty The property for the y coordinate being animated.
    @param path The <code>Path</code> to animate values along.
    @return An ObjectAnimator object that is set up to animate along <code>path</code>.]]>
      </javadoc>
    </method>

Rather than processing the jni-signature attribute of the method, these
parameter elements can be used to produce more reliable type information
for our reference documentation links.

[pjcollins]

The following docs diff is dependent on a few other changes landing in android-api-docs first, but can be used as a reference for these changes:
https://gist.github.com/pjcollins/aea5200cad24c4386f59e3cf79427ef2