Number field: Adding new options for placeholder, prepend and append

Signed-off-by: Elliot Condon <e@elliotcondon.com>
Core: Prevent decimal places from being converted to floats

Signed-off-by: Elliot Condon <e@elliotcondon.com>
Text Field: Allow 0 string to show in prepend / append

Signed-off-by: Elliot Condon <e@elliotcondon.com>
Core: Updated CSS for number field in prepend / append

Signed-off-by: Elliot Condon <e@elliotcondon.com>