Add PIOASM test cases for error and valid outputs

Added new test cases to cover invalid character errors, invalid .lang_opt usage, unknown directive errors, and a valid JSON output scenario for pioasm. These tests improve coverage of error handling and output formatting.

tools/pioasm/test/errors/general/test_invalid_character_errors.pio

@@ -0,0 +1,13 @@
+// run: pioasm input.pio
+.program invalid_character
+@
+    nop
+// -- Output
+// Command: pioasm input.pio
+// Exit code: 1
+// Stdout:
+// Stderr:
+// input.pio:3.1: invalid character: @
+//     3 | @
+//       | ^
+// 

tools/pioasm/test/errors/general/test_lang_opt_invalid_errors.pio

@@ -0,0 +1,16 @@
+// run: pioasm input.pio
+.program lang_opt_invalid
+.lang_opt python foo = "unterminated
+    nop
+// -- Output
+// Command: pioasm input.pio
+// Exit code: 1
+// Stdout:
+// Stderr:
+// input.pio:3.24: invalid character: "
+//     3 | .lang_opt python foo = "unterminated
+//       |                        ^
+// input.pio:3.1-22: expected format is .lang_opt language option_name = option_value
+//     3 | .lang_opt python foo = "unterminated
+//       | ^~~~~~~~~~~~~~~~~~~~~~
+// 

tools/pioasm/test/errors/general/test_unknown_directive_errors.pio

@@ -0,0 +1,13 @@
+// run: pioasm input.pio
+.program unknown_directive
+.bogus 1
+    nop
+// -- Output
+// Command: pioasm input.pio
+// Exit code: 1
+// Stdout:
+// Stderr:
+// input.pio:3.1-6: unknown directive .bogus
+//     3 | .bogus 1
+//       | ^~~~~~
+// 

tools/pioasm/test/valid/output/test_output_json_full_valid.pio

@@ -0,0 +1,57 @@
+// run: pioasm -o json input.pio
+.define PUBLIC global_const 7
+
+.program format_test
+.origin 4
+.side_set 2 opt pindirs
+.define PUBLIC prog_const 3
+public entry:
+.wrap_target
+    nop side 1
+.wrap
+
+.program second_prog
+    nop
+// -- Output
+// Command: pioasm -o json input.pio
+// Exit code: 0
+// Stdout:
+// {
+// 	"publicSymbols": {
+// 		"global_const": 7
+// 	},
+// 	"programs": [
+// 		{
+// 			"name": "format_test",
+// 			"wrapTarget": 0,
+// 			"wrap": 0,
+// 			"origin": 4,
+// 			"sideset": {"size": 3, "optional": true, "pindirs": true},
+// 			"publicSymbols": {
+// 				"prog_const": 3
+// 			},
+// 			"publicLabels": {
+// 				"entry": 0
+// 			},
+// 			"instructions": [
+// 				{"hex": "B442"}
+// 			]
+// 		},
+// 		{
+// 			"name": "second_prog",
+// 			"wrapTarget": 0,
+// 			"wrap": 0,
+// 			"origin": -1,
+// 			"sideset": {"size": 0, "optional": false, "pindirs": false},
+// 			"publicSymbols": {
+// 			},
+// 			"publicLabels": {
+// 			},
+// 			"instructions": [
+// 				{"hex": "A042"}
+// 			]
+// 		}
+// 	]
+// }
+// 
+// Stderr: