fix: review cargo config

* move package settings into correct table
* move .cargo into wasm dir
* set "std" for burn

wasm/inference-models/.cargo/config.toml

@@ -1,7 +0,0 @@
-[target.wasm32-unknown-unknown]
-rustflags = [
-    "-Ctarget-feature=+simd128,+bulk-memory,+reference-types",
-    '--cfg', 'getrandom_backend="wasm_js"',
-    "--cfg=has_std",
-    "-Zthreads=6"
-]