Add support for onxxx HTML events

[benoit74]

Fix #209

Changes:

• add support for onxxx events, with same logic as wabac (https://github.com/webrecorder/wabac.js/blob/main/src/rewrite/html.js#L143-L145)
• add few test cases on test website for onclick HTML events
• fix a test which was failing due to a previously introduced trick

[rgaudin]

LGTM

Do we have a ticket for improving client side dynamic rewrite?
I know it's overkill at this point but there are ways like storing a sorted list of all entries paths that might be discussed in the future.

[benoit74]

Do we have a ticket for improving client side dynamic rewrite?

I just opened #276 ; I'm not sure it is a good idea to implement this, at least there are some drawbacks to discuss / find countermeasures.