add writeConstraint range validation

[kossnikita]

fixes rust-embedded/svd#232

[burrbull]

I don't it is good to validate field during modification.
There are can be several bugs in one field fixable by different patches.
In this case check will fault between these patches.

[kossnikita]

Is it better to add validation to svd_encoder::encode?

[burrbull]

I'm not sure. Most of validation work during parsing (for example by svd2rust or svdtools convert).

Maybe just svdtools validate tool?

[kossnikita]

I think it would be wrong if svdtools patch produces an invalid file (even if the patch is invalid)

[kossnikita]

Maybe just svdtools validate tool?

#153
It won't do the same?

[burrbull]

I think it would be wrong if svdtools patch produces an invalid file (even if the patch is invalid)

resonable. Possilbly some optional flag like svdtools patch --post-validate.