In JavaScript, the following computation introduces numerical errors:
```
Math.pow(10, -4) = 0.00009999999999999999
Math.pow(10, -5) = 0.000009999999999999999
```
In the context of `round_decimals`, such errors propagate to
`round_precision`, ultimately leading to inconsistencies between Python
and JS (see #47300 for detailed use case).
Instead of computing `Math.pow(10, decimals)`, we parse the scientific
notation to prevent such inaccuracies.
We also introduce tests in line with the Python tests.
opw-2205092
closesodoo/odoo#47694
X-original-commit: cb471897bfa08d1fee6a9f49e90d9c120e1733fc
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>