项目从Angular8升级到angualr9出现错误：Could not find @angular-devkit/build-angular:dev-server

错误详情：An unhandled exception occurred: Could not find the implementation for builder @angular-devkit/build-angular:dev-server.

错误原因：本地的angular-cli 和 @angular-devkit/build-angular 不匹配。如果强制升级本地的angular-cli 会导致这个问题。

解决方案：升级到最新库@angular-devkit/build-angular

执行名令：npm i --save-dev @angular-devkit/build-angular@latest