[llvm-cov] Improvements for summary report generated in HTML format.

Summary:
This commit adds the following changes:

1) coverage numbers are aligned to the left and padded with spaces in order to
provide better readability for percentage values, e.g.:

```
file1     |  89.13% (123 / 2323)    | 100.00% (55 / 55)    |   9.33% (14545 / 234234)
file_asda |   1.78% ( 23 / 4323)    |  32.31% (555 / 6555) |  67.89% (1545 / 2234)
fileXXX   | 100.00% (12323 / 12323) | 100.00% (555 / 555)  | 100.00% (12345 / 12345)
```

2) added "hover" attribute to CSS for highlighting table row under mouse cursor
see screenshot attached to the phabricator review page

{F5764813}

3) table title row and "totals" row now use bold text

Reviewers: vsk, morehouse

Reviewed By: vsk

Subscribers: kcc, llvm-commits

Differential Revision: https://reviews.llvm.org/D42093

llvm-svn: 323892

0 files changed, 0 insertions, 0 deletions