`@lifetime(borrow self)` loses whitespace when pretty printed

[natecook1000]

The @lifetime attribute allows different forms of parameters, with several being of the form:

@lifetime(<dependency-kind> <target>)

swift-format is currently collapsing that form into something invalid by removing the whitespace between the dependency kind and the target. That is:

@lifetime(borrow self)
init() {}

becomes:

@lifetime(borrowself)
init() {}

See the lifetime dependency proposal for more details.