simpleperf: add progressbar for html report.

Currently, report_html.js uses setTimeout(0) to draw details in idle
time. But it can make the UI not responsive. So switch to use
progressbar when drawing details.

Also switch to use bootstrap4.

Bug: 109943459
Test: run report_html.py manually.
Test: run test.py TestExamplePureJava.test_report_html.

Change-Id: I0ed30bd4326087502af799a702076851abb5f63f
2 files changed