Add a resolveEnvVars option to .zap package.pathRelativity (project-chip#891)

This allows variables like $CHIP_ROOT to be used, which is needed when
the chip codebase is a submodule of the repository the zap file is in.

Throw an error when any variable used fails resolving.

Author: q-thla

src-electron/util/util.js

@@ -444,6 +444,16 @@ function createAbsolutePath(relativePath, relativity, zapFilePath) {
       return path.join(os.homedir(), relativePath)
     case dbEnum.pathRelativity.relativeToZap:
       return path.join(path.dirname(zapFilePath), relativePath)
+    case dbEnum.pathRelativity.resolveEnvVars:
+      for (let key in process.env) {
+        if (Object.prototype.hasOwnProperty.call(process.env, key)) {
+          relativePath = relativePath.replaceAll('$' + key, process.env[key])
+          relativePath = relativePath.replaceAll('${' + key + '}', process.env[key])
+        }
+      }
+      if (relativePath.indexOf('$') !== -1) {
+        throw new Error('resolveEnvVars: unable to resolve environment variables completely: ' + relativePath)
+      }
   }
   return relativePath
 }

src-shared/db-enum.js

@@ -84,6 +84,7 @@ exports.pathRelativity = {
   relativeToZap: 'relativeToZap',
   relativeToUserHome: 'relativeToHome',
   absolute: 'absolute',
+  resolveEnvVars: 'resolveEnvVars',
 }
 
 exports.wsCategory = {