consider selecting a matching name for like and ImplicitAs

[zygoloid]

As a mnemonic device, it may be useful to use the same spelling for like and the corresponding interface ImplicitAs, just as we use the same spelling for as and the corresponding interface As.

We should decide if we want to do this and pick what names we want:

• like/Like: impl StringRef as Like(String) and impl like String as Add(like String)
• implicit_as/ImplicitAs: impl StringRef as ImplicitAs(String) and impl implicit_as String as Add(implicit_as String)
• implicitly/Implicitly: impl StringRef as Implicitly(String) and impl implicitly String as Add(implicitly String)
• Something else. Suggestions please!

[chandlerc]

To clarify, this is a low-priority issue just to track revisiting the name at some point. It shouldn't block anything.