Re-instate the API export

After a discussion with blam I now understand the value of the SPI export so
have added it back in (albeit with some significant changes from the original)

https://discord.com/channels/687207715902193673/687207715902193679/855378432871759922

Signed-off-by: Andrew Shirley <andrew.shirley@sainsburys.co.uk>
Signed-off-by: blam <ben@blam.sh>

.changeset/good-hornets-hunt.md

@@ -57,6 +57,12 @@ jenkins:
   apiKey: ${JENKINS_PASSWORD}
 ```
 
+## Change javascript API
+
+As part of the above change, the javascript API exposed by the plugin as a possible place for customisation has changed.
+The ApiRef now has an id of `plugin.jenkins.service2` and has entity-based functions to match the nedpoints exposed by
+the new backend plugin
+
 ## Change BuildWithStepsPage route
 
 The plugin originally provided a route to view a particular build of a particular branch so that if you wanted to view

plugins/jenkins/src/index.ts

@@ -27,3 +27,4 @@ export {
   isJenkinsAvailable as isPluginApplicableToEntity,
 } from './components/Router';
 export { JENKINS_ANNOTATION } from './constants';
+export * from './api';