Rollup merge of #147000 - moturus:motor-os_stdlib_pr, r=tgross35

std: Add Motor OS std library port

Motor OS was added as a no-std Tier-3 target in
[PR 146848](https://github.com/rust-lang/rust/pull/146848) as x86_64-unknown-motor.

This PR adds the std library for Motor OS.

While the PR may seem large, all it does is proxy
std pal calls to [moto-rt](https://crates.io/crates/moto-rt). Where there is some non-trivial
code (e.g. thread::spawn), it is quite similar, often
identical, to what other platforms do.

library/Cargo.lock

@@ -166,6 +166,16 @@ dependencies = [
  "rustc-std-workspace-core",
 ]
 
+[[package]]
+name = "moto-rt"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "058a2807a30527bee4c30df7ababe971cdde94372d4dbd1ff145bb403381436c"
+dependencies = [
+ "rustc-std-workspace-alloc",
+ "rustc-std-workspace-core",
+]
+
 [[package]]
 name = "object"
 version = "0.37.3"
@@ -316,6 +326,7 @@ dependencies = [
  "hermit-abi",
  "libc",
  "miniz_oxide",
+ "moto-rt",
  "object",
  "panic_abort",
  "panic_unwind",