iconview entry selection enhancement

[rparth07]

• Intoduces icon-view entry selection json to send along with selection/activation instead of just selected index
• This information can be helpful in core side to know if any mouse key was pressed along with selection of item to execute relevant logic if exist.
• i.e sidebar->border popup dialog allows to overwrite borders if shift key was pressed along border item selection

Change-Id: I09ced62b58fb906abc7279fa2c77ba06a0743eab

This is follow-up of #13637 core patch require: https://gerrit.libreoffice.org/c/core/+/194688

Checklist

• [ ] I have run make prettier-write and formatted the code.
• [ ] All commits have Change-Id
• [ ] I have run tests with make check
• [ ] I have issued make run and manually verified that everything looks okay
• [ ] Documentation (manuals or wiki) has been updated or is not required