function shareMacro_(sourceScriptId, targetSpreadsheetUrl) {

  // Gets the source project content using the Apps Script API.
  const sourceProject = APPS_SCRIPT_API.get(sourceScriptId);
  const sourceFiles = APPS_SCRIPT_API.getContent(sourceScriptId);

  // Opens the target spreadsheet and gets its ID.
  const parentSSId = SpreadsheetApp.openByUrl(targetSpreadsheetUrl).getId();

  // Creates an Apps Script project that's bound to the target spreadsheet.
  const targetProjectObj = APPS_SCRIPT_API.create(sourceProject.title, parentSSId);

  // Updates the Apps Script project with the source project content.
  APPS_SCRIPT_API.updateContent(targetProjectObj.scriptId, sourceFiles);

}
Uses Apps Script API to copy source Apps Script project 
to destination Google Spreadsheet container.

@param {string} sourceScriptId - Script ID of the source project.
@param {string} targetSpreadsheetUrl - URL if the target spreadsheet.