Fix widths for literal values in Bundle literals (#4082)

* Fix widths for literal values in Bundle literals

Previously, the user-specified (or unspecified minimum width) of the
literal would be used in some operations like concatenation.

* Implicitly truncate too-wide literals in Bundle literals

This is to fix a bug in concatenation without breaking things relying on
implicit truncation. This will be a warning in newer versions of Chisel.