Account Output Builder allows setting Immutable Sender Feature

[PhilippGackstatter]

Account Output Builder allow setting Immutable Sender Feature, which should not be allowed.

Also investigate why serix does not throw an error when serializing an Account with such a feature.

Reported here.

Anchor Output Builder allows setting Sender Feature which is also incorrect.

Also consider requiring the serial number to be set in NewFoundryOutputBuilder, since the default of 0 is always invalid and users need to set the serial number explicitly upon foundry creation.