all: make emulator command a string instead of a []string

This matches the flash-command and is generally a bit easier to work
with.
This commit also prepares for allowing multiple formats to be used in
the emulator command, which is necessary for the esp32.

targets/arduino-nano.json

@@ -6,5 +6,5 @@
 		"-Wl,--defsym=_stack_size=512"
 	],
 	"flash-command": "avrdude -c arduino -p atmega328p -b 57600 -P {port} -U flash:w:{hex}:i",
-	"emulator": ["simavr", "-m", "atmega328p", "-f", "16000000"]
+	"emulator": "simavr -m atmega328p -f 16000000 {}"
 }

targets/arduino.json

@@ -7,5 +7,5 @@
 	],
 	"flash-command": "avrdude -c arduino -p atmega328p -P {port} -U flash:w:{hex}:i",
 	"serial-port": ["acm:2341:0043", "acm:2341:0001", "acm:2a03:0043", "acm:2341:0243"],
-	"emulator": ["simavr", "-m", "atmega328p", "-f", "16000000"]
+	"emulator": "simavr -m atmega328p -f 16000000 {}"
 }

targets/atmega1284p.json

@@ -13,5 +13,5 @@
         "targets/avr.S",
         "src/device/avr/atmega1284p.s"
     ],
-    "emulator": ["simavr", "-m", "atmega1284p", "-f", "20000000"]
+    "emulator": "simavr -m atmega1284p -f 20000000 {}"
 }

targets/cortex-m-qemu.json

@@ -5,5 +5,5 @@
 	"extra-files": [
 		"targets/cortex-m-qemu.s"
 	],
-	"emulator": ["qemu-system-arm", "-machine", "lm3s6965evb", "-semihosting", "-nographic", "-kernel"]
+	"emulator": "qemu-system-arm -machine lm3s6965evb -semihosting -nographic -kernel {}"
 }

targets/digispark.json

@@ -6,5 +6,5 @@
 		"-Wl,--defsym=_stack_size=128"
 	],
 	"flash-command": "micronucleus --run {hex}",
-	"emulator": ["simavr", "-m", "attiny85", "-f", "16000000"]
+	"emulator": "simavr -m attiny85 -f 16000000 {}"
 }

targets/gameboy-advance.json

@@ -24,5 +24,5 @@
 		"src/runtime/gc_arm.S"
 	],
 	"gdb": ["gdb-multiarch"],
-	"emulator": ["mgba", "-3"]
+	"emulator": "mgba -3 {}"
 }

targets/hifive1-qemu.json

@@ -4,5 +4,5 @@
 	"serial": "uart",
 	"default-stack-size": 4096,
 	"linkerscript": "targets/hifive1-qemu.ld",
-	"emulator": ["qemu-system-riscv32", "-machine", "sifive_e", "-nographic", "-kernel"]
+	"emulator": "qemu-system-riscv32 -machine sifive_e -nographic -kernel {}"
 }

targets/riscv-qemu.json

@@ -4,5 +4,5 @@
 	"build-tags": ["virt", "qemu"],
 	"default-stack-size": 4096,
 	"linkerscript": "targets/riscv-qemu.ld",
-	"emulator": ["qemu-system-riscv32", "-machine", "virt", "-nographic", "-bios", "none", "-kernel"]
+	"emulator": "qemu-system-riscv32 -machine virt -nographic -bios none -kernel {}"
 }

targets/wasi.json

@@ -13,6 +13,6 @@
 		"--stack-first",
 		"--no-demangle"
 	],
-	"emulator":      ["wasmtime"],
+	"emulator":      "wasmtime {}",
 	"wasm-abi":      "generic"
 }

targets/wasm.json

@@ -13,6 +13,6 @@
 		"--stack-first",
 		"--no-demangle"
 	],
-	"emulator":      ["node", "{root}/targets/wasm_exec.js"],
+	"emulator":      "node {root}/targets/wasm_exec.js {}",
 	"wasm-abi":      "js"
 }