targets: minimal uefi target support (#5452)

* runtime: split baremetal memory setup

* runtime: extract Windows PE globals scan helper

* compileopts,builder: add target linker flavor override

* machine,runtime,targets: add minimal uefi-amd64 target

* runtime,examples: add clean UEFI exit path test

* machine,x86: fix amd64 ABI stack handling

* machine/uefi: add CHAR16 conversion helpers

* machine/uefi: add loaded image protocol support

* runtime: add UEFI PE globals support

* machine,runtime,x86: add UEFI time and text output support

* machine,runtime,x86: add UEFI text and time support

* machine,runtime,examples: add UEFI text input support

* machine,examples: add UEFI graphics output support

* add rest of STOP methods (direct UEFI ABI only)

* runtime: fix UEFI sleep tick conversion

* machine/uefi: make text input waits cooperative

* address TestClangAttributes/uefi-amd64 failure

* address TestConfigLinkerFlavor bug

* uefi: move raw bindings to device package

* strip down implementation to bare minimum

* amd64: rename x86 package

* do git restore upstream/dev for src/net

* add smoketest for uefi-amd64; add required zeroSizeAllocPtr constant

* address PR issues: remove unused files; make putchar() insert '\r' before '\n'

* swap lines around

builder/builder_test.go

@@ -37,6 +37,7 @@ func TestClangAttributes(t *testing.T) {
 		"nintendoswitch",
 		"riscv-qemu",
 		"tkey",
+		"uefi-amd64",
 		"wasip1",
 		"wasip2",
 		"wasm",