Ajax: Don't treat array data as binary

Ajax: Don't treat array data as binary

PR gh-5197 started treating all non-string non-plain-object
`data` values as binary. However, `jQuery.ajax` also supports
arrays as values of `data`. This change makes regular arrays
no longer be considered binary data.

Surprisingly, we had no tests for array `data` values; otherwise,
we'd detect the issue earlier. This change also adds
a few such missing tests.

Closes gh-5203
Ref gh-5197