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.

src/commands/wast.rs

@@ -2,8 +2,8 @@
 
 use crate::CommonOptions;
 use anyhow::{Context as _, Result};
+use clap::Parser;
 use std::path::PathBuf;
-use structopt::{clap::AppSettings, StructOpt};
 use wasmtime::{Engine, Store};
 use wasmtime_wast::WastContext;
 
@@ -14,19 +14,18 @@ lazy_static::lazy_static! {
 }
 
 /// Runs a WebAssembly test script file
-#[derive(StructOpt)]
-#[structopt(
+#[derive(Parser)]
+#[clap(
     name = "wast",
-    version = env!("CARGO_PKG_VERSION"),
-    setting = AppSettings::ColoredHelp,
+    version,
     after_help = AFTER_HELP.as_str(),
 )]
 pub struct WastCommand {
-    #[structopt(flatten)]
+    #[clap(flatten)]
     common: CommonOptions,
 
     /// The path of the WebAssembly test script to run
-    #[structopt(required = true, value_name = "SCRIPT_FILE", parse(from_os_str))]
+    #[clap(required = true, value_name = "SCRIPT_FILE", parse(from_os_str))]
     scripts: Vec<PathBuf>,
 }