[BUGFIX] Allow "defaultValue" for select form elements

Allows the form editor to save the property "defaultValue" for
"Inspector-PropertyGridEditor" inspector editors. This rules for the
form element types "SingleSelect", "RadioButton", "MultiCheckbox"
and "MultiSelect".

Besides that a flaw in JavaScript is solved that truncated values
by one character (e.g. having "propert" instead of "property"), as
well as having a correct representation of objects and arrays when
initializing them in JavaScript.

Resolves: #85608
Resolves: #85670
Releases: master, 8.7
Change-Id: Ia82ee236e6becb36db13fb15e96c7caceab370d1
Reviewed-on: https://review.typo3.org/57728


Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>