Feature request: Complete suggestions using "l" in Vi mode

Basically what the title says.

It makes sense to complete suggestions using the "l" key in Vi mode, just like the Fish shell does.

Start by locating pgcli's Vi-mode key handling and the existing suggestion-completion behavior, then compare it with the Fish shell behavior described in the issue. Done means pressing "l" in Vi mode completes the current suggestion without breaking other editing or completion keys; verify this through the CLI's existing tests or an interactive pgcli session.

索引モデルが issue の本文から書いたものです。