[RFE] Automate - Expose max_retries override at instance level

[ghost]

When one creates a state machine, the maximum number of retries for a state is set at the class level. However, a use case of state machines is to create generic state machines where the state name is 'StateX' and URI is specified only at the instance level, not the class. In this case, to stay generic, one is tempted to set the maximum number of retries to a very high number for each state, to cover whatever situation at the instance level.

Allowing to override the maximum number of retries at the instance level would help creating generic state machine classes (scaffolds) with no maximum retries set, and then let the instance specify the maximum retries based on the actual URI.

According to @mkanoor, the max_retries can already be set at the instance level in the backend code, but the UI currently doesn't support it. So I create this issue to politely ask for someone to add this in th Classic UI.

XRef: ManageIQ/manageiq-automation_engine/issues/163
Associated BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1596338

[gmcculloug]

@miq-bot assign @h-kataria

[ghost]

Tried and tested. Works as expected.