New alr settings command to replace alr config

[Fabien-Chouteau]

This change is introduced to tackle the confusion between the configuration of the Alire commands and operations, and the configuration of crates.

alr config is still available and should work as before with the exception of a deprecation warning message.

[Fabien-Chouteau]

The other options would be to rename crate configuration into crate settings.

It would be trivial to change this releases currently in the index.
There are 288 occurrences of [configuration in the community index releases.
34 releases are defining configuration variables.
24 releases are setting configuration values.

[mosteo]

The other options would be to rename crate configuration into crate settings.

I like better alr settings and crate config than the other way around (so this PR). Also it seems less of a headache than breaking manifest compatibility. Also the config dir we create...

[Fabien-Chouteau]

Also it seems less of a headache than breaking manifest compatibility. Also the config dir we create...

Indeed, that would be the most annoying.

Note that there is a couple things I didn't change in this PR:

• -c (--config=ARG) Override configuration folder location global switch
• .alire/config.toml file
• ALR_CONFIG scenario variable
• The name of Alire.Config.* packages
• Default folder ~/.config/

[mosteo]

• -c (--config=ARG) Override configuration folder location global switch

Ouch. Maybe we can say "configuration settings" and leave as is. I don't see potential for confusion here.

• .alire/config.toml file

We could rename this one on the fly.

• ALR_CONFIG scenario variable

Ouch again. I would now document ALIRE_SETTINGS and use the old one as fallback, with warning.

• The name of Alire.Config.* packages

Internal, minor issue.

• Default folder ~/.config/

This one comes from XDG_CONFIG_HOME. On Windows we could start using AppData/Local or similar, like with the cache...