feat: Implement From<Verbosity> for tracing and log types

This makes it possible to just directly setup the log filter:

E.g.:
```rust
env_logger::Builder::new().filter_level(cli.verbosity.into()).init();
// or
tracing_subscriber::fmt().with_max_level(cli.verbosity).init();
```

examples/log.rs

@@ -5,14 +5,14 @@ use clap_verbosity_flag::Verbosity;
 #[derive(Debug, Parser)]
 struct Cli {
     #[command(flatten)]
-    verbose: Verbosity,
+    verbosity: Verbosity,
 }
 
 fn main() {
     let cli = Cli::parse();
 
     env_logger::Builder::new()
-        .filter_level(cli.verbose.log_level_filter())
+        .filter_level(cli.verbosity.into())
         .init();
 
     log::error!("Engines exploded");

examples/tracing.rs

@@ -5,14 +5,14 @@ use clap_verbosity_flag::Verbosity;
 #[derive(Debug, Parser)]
 struct Cli {
     #[command(flatten)]
-    verbose: Verbosity,
+    verbosity: Verbosity,
 }
 
 fn main() {
     let cli = Cli::parse();
 
     tracing_subscriber::fmt()
-        .with_max_level(cli.verbose.tracing_level_filter())
+        .with_max_level(cli.verbosity)
         .init();
 
     tracing::error!("Engines exploded");

src/log.rs

@@ -3,7 +3,7 @@
 // information.
 pub use log::{Level, LevelFilter};
 
-use crate::VerbosityFilter;
+use crate::{Verbosity, VerbosityFilter};
 
 impl From<VerbosityFilter> for LevelFilter {
     fn from(filter: VerbosityFilter) -> Self {
@@ -57,6 +57,18 @@ impl From<Option<Level>> for VerbosityFilter {
     }
 }
 
+impl From<Verbosity> for LevelFilter {
+    fn from(v: Verbosity) -> Self {
+        v.log_level_filter()
+    }
+}
+
+impl From<Verbosity> for Option<Level> {
+    fn from(v: Verbosity) -> Self {
+        v.log_level()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

src/tracing.rs

@@ -3,7 +3,7 @@
 // more information.
 pub use tracing_core::{Level, LevelFilter};
 
-use crate::VerbosityFilter;
+use crate::{Verbosity, VerbosityFilter};
 
 impl From<VerbosityFilter> for LevelFilter {
     fn from(filter: VerbosityFilter) -> Self {
@@ -57,6 +57,18 @@ impl From<Option<Level>> for VerbosityFilter {
     }
 }
 
+impl From<Verbosity> for LevelFilter {
+    fn from(v: Verbosity) -> Self {
+        v.tracing_level_filter()
+    }
+}
+
+impl From<Verbosity> for Option<Level> {
+    fn from(v: Verbosity) -> Self {
+        v.tracing_level()
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;