These properties have a very specific detail in their behavior, in that
the constructor's name is set to be "<init>". While this is OK for the
IR serialization, this may not always be expected in other cases, and
their rather common names (`name`, `fqNameSafe`) suggested that these
properties could be used in generic contexts.
Change all usages outside IR serialization to use
`IrDeclarationWithName.name` and nullable
`IrDeclarationWithName.fqNameWhenAvailable` instead
Move kotlin-stdlib-js project and the sources specific to the current backend to 'stdlib/js-v1' directory,
but leave sources that can be shared with the new IR backend in the common 'stdlib/js' location
with exception for 'stdlib/js/src/generated', which is used exclusively for current backend.
This simplifies sourceset configuration when building stdlib with the new backend.
Igor Chevdar