Bugfix/16181 number field amends

[i-just]

Description

In v4, if you type 5.6 into a number field which has decimals set to zero, the value stored in the DB is 5; the value displayed in the control panel and on the front end is also 5 (that’s because the decimals setting affected the type of column the data was saved to).
In v5, it’s

• stored as 5.6
• displayed on the front end as 5.6
• and in the control panel:
  • in the field and in element indexes as 6 if the preview format is “as decimal values” (default)
  • in the field as 6 and in element indexes 5.60 if the preview format is “as currency values”
  • in the field and in element indexes as 5.6 if the preview format is “unformatted”

Since we no longer rely on column types, normalisation should take care of ensuring the field’s decimals setting is respected.

Related issues

#16181