Eliminate Buildscript by publishing to gradlePluginPortal

[codeconsole]

if grails-gradle-plugin is published to gradlePluginPortal,

buildSrc/build.gradle
settings.gradle
and a buildscript { }

are no longer needed for Grails Apps.

Also remove need for

apply plugin:"org.grails.grails-web"
apply plugin:"org.grails.grails-gsp"

grails-gradle-plugin currently consists of

org.grails.grails-core
org.grails.grails-doc
org.grails.grails-plugin.properties
org.grails.grails-profile.properties
org.grails.grails-web.properties
org.grails.internal.grails-plugin-publish
org.grails.internal.grails-profile-publish

org.grails.grails-web should automatically be applied if org.grails:grails-web-url-mappings is present
org.grails.grails-gsp should automatically be applied if org.grails:grails-gsp is present

[davydotcom]

I suggest moving the contents of grails-web into the grails-core gradle plugin and simplifying some of the structure. A lot of plugins were split instead of just using config to enable/disable available tasks a plugin provides