Update WP core's jquery-serialize-object script

[jtsternberg]

The jquery-serialize-object script bundled with core is both old (2010), and lacks the ability to serialize nested form keys (i.e. name="name[value]").

I suggest we replace with this updated script instead: ​https://github.com/macek/jquery-serialize-object

[jtsternberg]

Replace serialize-object script w/ new and updated script and add minified version.

[jtsternberg]

Actually include the minified file this time.

[ericlewis]

Is this fully backwards compatible?

[desrosj]

I am going to close this out as a maybelater.

A ​search of the plugin directory returned 133 matches for jquery-serialize-object. The majority of the plugins have a very low number of active installs. A large number of the plugins matched are either false positives or the plugins including the library suggested in the ticket description themselves.

I'm also changing this to a low priority as jQuery development is not currently a priority. If someone comes across this ticket, would like to see this land in Core, and is willing to dedicate the time, please do reopen. Ideally:

• some tests would be written to confirm that the change would be 100% seamless and backwards compatible.
• The package would be installed using NPM for easier updating in the future (though the project is largely untouched in several years)
• Testing would be done to ensure no adverse affects if a plugin is also rolling their own version of the library.