RFR: 8184208: update class="striped" tables for accessibility

[Jonathan Gibbons]

Please review this auto-generated update to improve the accessibility of 
many of the tables
in the API docs for the java.base module.

The changes are just to the HTML markup for selected tables;
there is no change to the wording of any documentation.

This update was generated by a utility program that looks for tables 
using the
CSS style class "striped", and updates those tables as follows:

* header cells (<th>) in the <thead> now declare scope="col"
* the first data cell (<td>) in each row in the <tbody> are changed to <th>
     and declare scope="row".
     Although these cells are changed from <td> to <th>, the CSS still 
uses font-weight-normal for
     these cells.

The changes are in line with HTML 5 and WCAG 2.0.

This update does not include the following tables, which will be done 
separately (manually)

* tables with CSS class "borderless" (18), "plain" (37), or no class (6)
* tables in java.time.chrono (5): although these table use "striped",
     the first column does not contain unique values, and is therefore 
unsuited for the
     automated update

All the modifiied tables have been visually checked with an 
accessibility checker.

JBS: https://bugs.openjdk.java.net/browse/JDK-8184208
Webrev: http://cr.openjdk.java.net/~jjg/8184208/webrev.00/
API: http://cr.openjdk.java.net/~jjg/8184208/api.00/

-- Jon