Let's do this by modifying the mochitest retrigger action into a more
generic "test retrigger" action that supports both.
MozReview-Commit-ID: H3AbsJ58ASV
--HG--
extra : rebase_source : 048025a8665c6be54afa214355900a663fc84615
* This adds a kind: 'task' property to actions in actions.json
* This is already specified in the schema for actions.json
MozReview-Commit-ID: JmlAZouVPIf
--HG--
extra : rebase_source : 5855b9ddbfff2faa9e1db12fc1f60bbef3cccabb
Framework for defining actions in-tree that can be displayed
and triggered from Treeherder.
MozReview-Commit-ID: 3rvwgy2i4xu
--HG--
extra : rebase_source : beca394f4337aae4ab149e4db810352f57ec4988