simplify `mise settings` commands

[jdx]

here's what I would like to see:

$ mise settings # list all
a = true
b = true
$ mise settings a # get a value
true
$ mise settings a=false # set a value

I believe mise env-vars already works this way so we should be able to copy that logic.

[4ydx]

FYI

HAL:~/test$ mise version
2024.1.14 linux-x64 (187cc24 2024-01-09)
HAL:~/test$ mise env-vars a=b
HAL:~/test$ mise env-vars
a=b ~/test/.mise.toml
HAL:~/test$ mise env-vars a
error: invalid value 'a' for '[ENV_VARS]...'

For more information, try '--help'.

Are you wanting env-vars to also have "get a value" functionality?

[jdx]

definitely