Support new association methods for belongs_to and has_one

[tk0miya]

Since v7.0, #{association}_changed? and #{association}_previously_changed? methods were generated to the belongs_to associations.

In addition, since v7.1, reset_#{association} was also generated to both has_one and belongs_to associations.

It would be better to support them on rbs_rails.

refs:

• https://github.com/rails/rails/pull/42751
• https://github.com/rails/rails/pull/46165