Added test for the remaining units

[AleexCaires]

Added Latest tests for [remToPt, perToPt, ptToPer, perToPx, pxToPer]

[Mario-Duarte]

I have simplified the test file for useConvertUnits hook and fixed a mistake where the defaultSize referring to the default browser font-size was not taken into account when converting from points to rems and rems to points.

The correct way to find the ratio is to divide the defaultSize by 1.333333333333333, leading to the formula of:

// PT to REM
Math.round(((size * (1.333333333333333/defaultSize)) + Number.EPSILON) * 1000 ) / 1000;

and

// REM to PT
Math.round(((size / (1.333333333333333/defaultSize) ) + Number.EPSILON) * 1000 ) / 1000;

Apart from this, everything is LGTM
👏

[Mario-Duarte]

Added a few amends and added my comments previusly