Extract native methods into isolated classes

StaticLayout/MeasuredParagraph uses native methods which is a pain point
of porting TextView to JetPack.
To make minimize the dependency to the native methods, extract native
methods and put them into a thin wrapper class.

The performance impact is limited:

android.text.StaticLayoutPerfTest:
    PrecomputedText Balanced Hyphenation  :    602 ->    644: ( +42, +7.0%)
    PrecomputedText Balanced NoHyphenation:    457 ->    476: ( +19, +4.2%)
    PrecomputedText Greedy Hyphenation    :    397 ->    412: ( +15, +3.8%)
    PrecomputedText Greedy NoHyphenation  :    397 ->    411: ( +14, +3.5%)
    RandomText Balanced Hyphenation       : 17,594 -> 17,715: (+121, +0.7%)
    RandomText Balanced NoHyphenation     :  7,146 ->  7,236: ( +90, +1.3%)
    RandomText Greedy Hyphenation         :  7,125 ->  7,196: ( +71, +1.0%)
    RandomText Greedy NoHyphenation       :  7,099 ->  7,187: ( +88, +1.2%)
  draw
    PrecomputedText NoStyle               :    614 ->    628: ( +14, +2.3%)
    PrecomputedText Style                 :    778 ->    826: ( +48, +6.2%)
    RandomText NoStyle                    :    537 ->    540: (  +3, +0.6%)
    RandomText Style                      :    786 ->    759: ( -27, -3.4%)

Bug: N/A
Test: atest CtsWidgetTestCases:EditTextTest
    CtsWidgetTestCases:TextViewFadingEdgeTest
    FrameworksCoreTests:TextViewFallbackLineSpacingTest
    FrameworksCoreTests:TextViewTest FrameworksCoreTests:TypefaceTest
    CtsGraphicsTestCases:TypefaceTest CtsWidgetTestCases:TextViewTest
    CtsTextTestCases FrameworksCoreTests:android.text
    CtsWidgetTestCases:TextViewPrecomputedTextTest

Change-Id: I976df4db63be241af395dd30dd94182f76bdae53