Allow overriding remapped debug configuration via debug_custom.json

Some of the data from the `arduino-cli debug --info` output does not match exactly with the launch.json format required
by the IDE's debugger. For this reason, some remapping of the data is required.

The user can adjust the debugger configuration via a debug_custom.json file in the sketch project. The data from this
file is merged into the base data provided by `arduino-cli debug --info`. The data from debug_custom.json should
override the base data where there is overlap.

Previously the override did not work for the remapped Arduino CLI data since the remapping was applied after merging the
debug_custom.json data, which caused the debug_custom.json data to be overridden by that subset of the Arduino CLI data.
The bug is fixed by performing the remapping before merging the debug_custom.json data.

Author: per1234

Diff for: src/debug.ts

@@ -306,7 +306,8 @@ async function mergeLaunchConfig(
     (config) => config.configId === configId
   );
   const name = createName(board, programmer);
-  const launchConfig = {
+  // Create base configuration data
+  let launchConfig = {
     configId,
     cwd: '${workspaceRoot}',
     request: 'launch',
@@ -315,17 +316,26 @@ async function mergeLaunchConfig(
     ...(debugInfo.customConfigs
       ? debugInfo.customConfigs[cortexDebug] ?? {}
       : {}),
-    ...(customConfig ? customConfig : {}),
     name,
   };
+
+  // Remap Arduino CLI debug config properties to launch.json keys
   replaceValue('serverPath', 'serverpath', launchConfig);
   replaceValue('server', 'servertype', launchConfig);
   replaceValue('toolchainPath', 'armToolchainPath', launchConfig);
   replaceValue('serverConfiguration.scripts', 'configFiles', launchConfig);
+  // Remove unused Arduino CLI debug config data
   unsetValue(launchConfig, 'customConfigs');
   unsetValue(launchConfig, 'serverConfiguration');
   unsetValue(launchConfig, 'programmer'); // The programmer is not used by the debugger https://github.com/arduino/arduino-cli/pull/2391
   unsetValue(launchConfig, 'toolchain'); // The toolchain is also unused by IDE2 or the cortex-debug VSIX
+
+  // Merge configuration from debug_custom.json
+  launchConfig = {
+    ...launchConfig,
+    ...(customConfig ? customConfig : {}),
+  };
+
   return launchConfig;
 }