function addGlobalUsage(globalsConfig, identifierPath, identifierUse) {
  if (globalsConfig.has(identifierPath) && identifierUse !== 'write') {
    return
  }
  globalsConfig.set(identifierPath, identifierUse)
}
Add variable to results, if not already set

@param {Map<string, import('lavamoat-core').GlobalPolicyValue>} globalsConfig
@param {string} identifierPath
@param {import('lavamoat-core').GlobalPolicyValue} identifierUse