KtFieldCurrency: write tests for cursor position behavior

[carsoli]

Write component tests, listen on inputRef, and cursor position after user changes

make sure we satisfy what we expect in the cases below

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Useful for Testing KtFieldCurrency

the cursor is represented as _

Cursor Position

Input	Output	Remarks
_12.34	5_12.34
1_2.34	15_2.34
12_.34	125_.34
12._34	125._34
12.3_4	123.5_4
12.34_	123.45_

UI Insertion

Input	Output	Remarks
_12.34	512.34
1_2.34	152.34
12_.34	125.34
12._34	12.534	shift number left
12.3_4	12.354	shift number left
12.34_	12.345	shift number left

UI Deletion with Backspace

Input	Output	Remarks
_12.34	12.34
1_2.34	2.34
12_.34	1.34
12._34	12_.34	reinsert dot
12.3_4	1.2_4
12.34_	1.23_
1.23_	0.12_	add leading zero

Editing(/Pasting)

Input	Output	Remarks
1	0.01	add leading zero