Note that the new version of `eslint-plugin-import` contains support
for ESLint 9.
Moreover, the new version of Babel removed the leading space for import
comments (see https://github.com/babel/babel/pull/16780), so we update
the corresponding test expectation to match this.
Fixes a part of #17928.
This commit updates the Babel plugin to:
- apply the same flattening logic that we already
have for blocks, to flatten blocks nested inside
class static blocks
- remove class static blocks when, after flattening
all the blocks they contain, they are empty.
Before this commit, the transform output was the
same as the input.
This only happens when it's safe to do so. The exceptions are:
- when the class extends another subclass: removing the constructor would remove the error about the missing super() call
- when there are default parameters, that could have side effects
- when there are destructured prameters, that could have side effects
