clang-format: [JS] sort import aliases. Users can define aliases for long...

clang-format: [JS] sort import aliases. Users can define aliases for long symbols using import aliases:

    import X = A.B.C;

Previously, these were unhandled and would terminate import sorting.
With this change, aliases sort as their own group, coming last after all
other imports.

Aliases are not sorted within their group, as they may reference each
other, so order is significant.

This reverts commit f750c3d9. It fixes
the msan issue by not parsing past the end of the line when handling
import aliases.

Differential Revision: https://reviews.llvm.org/D118446