Support multiline cmds in YAML configuration

Add support for multiline `cmd` configurations allowing for nicer looking configuration YAML files.

config.example.yaml

@@ -4,36 +4,38 @@ healthCheckTimeout: 60
 
 models:
   "llama":
-    cmd: "models/llama-server-osx --port 8999 -m models/Llama-3.2-1B-Instruct-Q4_K_M.gguf"
-    proxy: "http://127.0.0.1:8999"
+    cmd: >
+      models/llama-server-osx
+      --port 8999
+      -m models/Llama-3.2-1B-Instruct-Q4_K_M.gguf
+    proxy: http://127.0.0.1:8999
 
     # list of model name aliases this llama.cpp instance can serve
     aliases:
-    - "gpt-4o-mini"
+    - gpt-4o-mini
 
     # check this path for a HTTP 200 response for the server to be ready
-    checkEndpoint: "/health"
+    checkEndpoint: /health
 
   "qwen":
-    cmd: "models/llama-server-osx --port 8999 -m models/Qwen2.5-1.5B-Instruct-Q4_K_M.gguf"
-    proxy: "http://127.0.0.1:8999"
+    cmd: models/llama-server-osx --port 8999 -m models/Qwen2.5-1.5B-Instruct-Q4_K_M.gguf
+    proxy: http://127.0.0.1:8999
     aliases:
-    - "gpt-3.5-turbo"
+    - gpt-3.5-turbo
 
   "simple":
     # example of setting environment variables
     env:
-      - "CUDA_VISIBLE_DEVICES=0,1"
-      - "env1=hello"
-    cmd: "build/simple-responder --port 8999"
-    proxy: "http://127.0.0.1:8999"
+      - CUDA_VISIBLE_DEVICES=0,1
+      - env1=hello
+    cmd: build/simple-responder --port 8999
+    proxy: http://127.0.0.1:8999
 
     # use "none" to skip check. Caution this may cause some requests to fail
     # until the upstream server is ready for traffic
-    checkEndpoint: "none"
+    checkEndpoint: none
 
   # don't use this, just for testing if things are broken
   "broken":
-    cmd: "models/llama-server-osx --port 8999 -m models/doesnotexist.gguf"
-    proxy: "http://127.0.0.1:8999"
-
+    cmd: models/llama-server-osx --port 8999 -m models/doesnotexist.gguf
+    proxy: http://127.0.0.1:8999