feat: Replace log with tracing

Replaces `log` with `tracing` and the custom logger with
`tracing_subscriber::Fmt`.

Adding support for re-configuring the logger at run-time and
removing the old logger format.

Signed-off-by: Jonathan Woollett-Light <jcawl@amazon.co.uk>

Author: Jonathan Woollett-Light

Cargo.lock

@@ -21,6 +21,8 @@ mmds = { path = "../mmds" }
 seccompiler = { path = "../seccompiler" }
 utils = { path = "../utils" }
 vmm = { path = "../vmm" }
+tracing = "0.1.37"
 
 [dev-dependencies]
 libc = "0.2.117"
+log = "0.4.19"

src/api_server/Cargo.toml

@@ -3,7 +3,7 @@
 
 use std::fmt::Debug;
 
-use logger::{error, info, log_enabled, Level};
+use logger::{error, info, Level};
 use micro_http::{Body, Method, Request, Response, StatusCode, Version};
 use serde::ser::Serialize;
 use serde_json::Value;
@@ -232,7 +232,7 @@ fn describe(method: Method, path: &str, body: Option<&Body>) -> String {
         ("/cpu-config", Some(payload_value)) => {
             // If the log level is at Debug or higher, include the CPU template in
             // the log line.
-            if log_enabled!(Level::Debug) {
+            if tracing::enabled!(Level::DEBUG) {
                 describe_with_body(method, path, payload_value)
             } else {
                 format!(