Description

permits the direnv module's *_msg segments to use the formatter:

• switches from map to map_meta
• introduces a warning if the rc_path isn't UTF-8 (reasonably this shouldn't be an issue?)

Motivation and Context

as detailed in #6153, it's nice to have colors for quick glancing, and not having the ability to format segments is an inconsistency with other modules

closes #6153

Screenshots (if appropriate):

using the following config:

[direnv]
disabled = false

allowed_msg = "[allowed](bold green)"
not_allowed_msg = "[not allowed](bold yellow)"
denied_msg = "[denied](bold red)"

loaded_msg = "[loaded](bold green)"
unloaded_msg = "[unloaded](bold red)"

format = "$allowed $loaded"

before:

after:

How Has This Been Tested?

• the msg_formatting test in the direnv module passes on linux
• the above screenshots/config

testing should be trivial on other platforms, but these changes shouldn't be platform-dependent

• I have tested using MacOS
• I have tested using Linux
• I have tested using Windows

Checklist:

• I have updated the documentation accordingly.
  likely not necessary, as none of the other modules mention that their variables can also be formatted strings
• I have updated the tests accordingly.