Add SSH user parameter (#1685)

* Add a configurable SSH user

* Update docs with param

* Indentation of readme

* formatting woes

* Update src/url-helper.ts

Co-authored-by: Josh Gross <joshmgross@github.com>

* Update action.yml

Co-authored-by: Josh Gross <joshmgross@github.com>

* Update genfiles

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Co-authored-by: Josh Gross <joshmgross@github.com>

src/url-helper.ts

@@ -12,7 +12,8 @@ export function getFetchUrl(settings: IGitSourceSettings): string {
   const encodedOwner = encodeURIComponent(settings.repositoryOwner)
   const encodedName = encodeURIComponent(settings.repositoryName)
   if (settings.sshKey) {
-    return `git@${serviceUrl.hostname}:${encodedOwner}/${encodedName}.git`
+    const user = settings.sshUser.length > 0 ? settings.sshUser : 'git'
+    return `${user}@${serviceUrl.hostname}:${encodedOwner}/${encodedName}.git`
   }
 
   // "origin" is SCHEME://HOSTNAME[:PORT]