cmd/swarm, swarm: cross-platform Content-Type detection (#17782)

- Mime types generator (Standard "mime" package rely on system-settings, see mime.osInitMime)
- Changed swarm/api.Upload:
    - simplify I/O throttling by semaphore primitive and use file name where possible
    - f.Close() must be called in Defer - otherwise panic or future added early return will cause leak of file descriptors
    - one error was suppressed

Makefile

@@ -57,6 +57,9 @@ devtools:
 	@type "solc" 2> /dev/null || echo 'Please install solc'
 	@type "protoc" 2> /dev/null || echo 'Please install protoc'
 
+swarm-devtools:
+	env GOBIN= go install ./cmd/swarm/mimegen
+
 # Cross Compilation Targets (xgo)
 
 geth-cross: geth-linux geth-darwin geth-windows geth-android geth-ios