Update to clap 3.* (#4082)

* Update to clap 3.0

This commit migrates all CLI commands internally used in this project
from structopt/clap2 to clap 3. The intent here is to ensure that we're
using maintained versions of the dependencies as structopt and clap 2
are less maintained nowadays. Most transitions were pretty
straightforward and mostly dealing with structopt/clap3 differences.

* Fix a number of `cargo deny` errors

This commit fixes a few errors around duplicate dependencies which
arose from the prior update to clap3. This also uses a new feature in
`deny.toml`, `skip-tree`, which allows having a bit more targeted
ignores for skips of duplicate version checks. This showed a few more
locations in Wasmtime itself where we could update some dependencies.

cranelift/serde/src/clif-json.rs

@@ -21,7 +21,7 @@
     )
 )]
 
-use clap::{App, Arg, SubCommand};
+use clap::Parser;
 use cranelift_codegen::ir::Function;
 use cranelift_reader::parse_functions;
 use std::fs::File;
@@ -54,50 +54,40 @@ fn call_de(file: &File) -> Result<(), String> {
     Ok(())
 }
 
-fn main() {
-    let matches = App::new("Cranelift JSON serializer/deserializer utility")
-        .subcommand(
-            SubCommand::with_name("serialize")
-                .display_order(1)
-                .about("Serializes Cranelift IR into JSON.")
-                .arg(Arg::with_name("pretty").short("p").help("pretty json"))
-                .arg(
-                    Arg::with_name("FILE")
-                        .required(true)
-                        .value_name("FILE")
-                        .help("Input file for serialization"),
-                ),
-        )
-        .subcommand(
-            SubCommand::with_name("deserialize")
-                .about("Deserializes Cranelift IR into JSON.")
-                .arg(
-                    Arg::with_name("FILE")
-                        .required(true)
-                        .value_name("FILE")
-                        .help("Input file for deserialization"),
-                ),
-        )
-        .get_matches();
+/// Cranelift JSON serializer/deserializer utility
+#[derive(Parser, Debug)]
+#[clap(about)]
+enum Args {
+    /// Serializes Cranelift IR into JSON
+    Serialize {
+        /// Generate pretty json
+        #[clap(long, short)]
+        pretty: bool,
 
-    let res_serde = match matches.subcommand() {
-        ("serialize", Some(m)) => {
-            let mut file =
-                File::open(m.value_of("FILE").unwrap()).expect("Unable to open the file");
+        /// Input file for serialization
+        file: String,
+    },
+    /// Deserializes Cranelift IR into JSON
+    Deserialize {
+        /// Input file for deserialization
+        file: String,
+    },
+}
+
+fn main() {
+    let res_serde = match Args::parse() {
+        Args::Serialize { pretty, file } => {
             let mut contents = String::new();
+            let mut file = File::open(file).expect("Unable to open the file");
             file.read_to_string(&mut contents)
                 .expect("Unable to read the file");
 
-            match m.occurrences_of("pretty") {
-                0 => call_ser(&contents, false),
-                _ => call_ser(&contents, true),
-            }
+            call_ser(&contents, pretty)
         }
-        ("deserialize", Some(m)) => {
-            let file = File::open(m.value_of("FILE").unwrap()).expect("Unable to open the file");
+        Args::Deserialize { file } => {
+            let file = File::open(file).expect("Unable to open the file");
             call_de(&file)
         }
-        _ => Err("Invalid subcommand.".to_string()),
     };
 
     if let Err(mut msg) = res_serde {