Emit FIRRTL bulk connects even for "input" wires

[jackkoenig]

Fixes #4218

One can question the need for this, as it's just making <> not error in a few more cases. The main motivation is that #4205 causes some existing uses of <> that used to work no longer work. It's an unnecessary breakage that is fixed by this change.

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Type of Improvement

• Bugfix

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[dtzSiFive]

💯

[mwachs5]

i never thought that <> was very sound for connecting two wires, so this is no worse than before 🤷‍♀️

[jackkoenig]

Until recently, I didn't know it even could work for two wires. As I mention in #4218, it does because of the special logic to sometimes emit FIRRTL bulk connects. So that work which was intended to be purely an optimization and not API visible actually extended the <> API in some funky ways.

This PR just makes it slightly more consistent in its funkiness 😇