Add missing .form-label classes in BS5 forms

[maciag-m]

According to BS5 docs, form labels should contain .form-label class to be displayed correctly. Without it, the space between label and field is too small.

Before:

After:

[long-blade]

@pascalbaljet please merge this. bs4 to bs5 has this minor change to the form labels

[Rattone]

@maciag-m isn't it better to add this class as default in the label component?

@pascalbaljet is this repo active? need reviewer or some help?