build: add figment for multi-provider configuration

Author: lmmx

Cargo.lock

@@ -96,6 +96,7 @@ tracing = { workspace = true }
 tracing-subscriber = { version = "0.3.20", features = ["env-filter"] }
 unicode-width = { version = "0.2.0" }
 which = { version = "8.0.0" }
+figment = { version = "0.10.19", features = ["env", "toml", "yaml"] }
 
 [target.'cfg(unix)'.dependencies]
 prek-pty = { workspace = true }