Un-deprecate BsButton's buttonType argument

[simonihmig]

Due to emberjs/ember.js#18232 we still support the attribute-argument buttonType in current 4.0 RCs, so remove the deprecation here to not cause folks to refactor to anything that will actually not work correctly.

[jelhan]

Very sad that this bug hasn't been fixed upstream yet. It's very likely to cause confusion. 😞

[RobbieTheWagner]

@simonihmig @jelhan so does this mean buttonType is required? We were using type and relying on splattributes, but that doesn't seem to work anymore.

[jelhan]

Yes. The bug is still not fixed in Glimmer VM.

[RobbieTheWagner]

I believe buttonType is no longer documented. If that is the case, we should add it back to the docs.

[jelhan]

I believe buttonType is no longer documented. If that is the case, we should add it back to the docs.

Good catch. Would appreciate a PR if you have the time. Documentation should be available in git history.