* bump Gradle Node Plugin version
* add Gradle convention plugin, with configurations, for sharing base-frontend files between subprojects
* refactor how files are copied into base-plugin project (use generated resource dir and Sync task - this will better ensure copied files are up-to-date)
* remove empty & unused subproject `:plugins:base:search-component`
* remove .gitignore, no longer needed (instead, files are synced to build dir)