async handleEntrypoint() {
    if (this.entrypoint) {
      const entrypointPath = path.resolve(this.templateContentDir, this.entrypoint);
      if (!(await exists(entrypointPath))) {
        throw new Error(`Template entrypoint "${entrypointPath}" couldn't be found.`);
      }
      if (this.output === 'fs') {
        await this.generateFile(this.asyncapi, path.basename(entrypointPath), path.dirname(entrypointPath));
        await this.launchHook('generate:after');
      } else if (this.output === 'string') {
        return await this.renderFile(this.asyncapi, entrypointPath);
      }
    } else {
      await this.generateDirectoryStructure(this.asyncapi);
    }
  }
Handles the logic for the template entrypoint.

If an entrypoint is specified:
- Resolves the absolute path of the entrypoint file.
- Throws an error if the entrypoint file doesn't exist.
- Generates a file or renders content based on the output type.
- Launches the 'generate:after' hook if the output is 'fs'.

If no entrypoint is specified, generates the directory structure.

@async
@returns {Promise<void>} A promise that resolves when the entrypoint logic is completed.