The protocol is not consistent on events that notify executions

[e-backmark-ericsson]

This issue was raised as a result of a discussion during the CDEvents WG on Jan 30th, 2023

These event subjects all represent executions of some kind, as they can all be started and finished:

• pipelineRun
• taskRun
• build
• testCase
• testSuite

The protocol is not consistent regarding those subjects or their predicates though:

• All of them have the predicates started and finished, but just some of them have the predicate queued
• The names of the subjects sometimes contain the suffix "Run" and sometimes not. It makes somewhat sense to not add "Run" to a "build" subject, since a build can be interpreted as a verb, but the testCase and testSuite subjects should probably include the "Run" suffix to be consistent with taskRun and pipelineRun. A clear naming convention for events that represent executions should be written as well, to not end up in such inconsistencies ahead.

Furthermore, none of the subjects above have a predicate that would signal that the subject has left the queue. A subject that has been queued would eventually get started, but there seems to be a need to also be able to signal that the subject has been dequeued and thus is not anymore expected to be started. The predicate to use here should proposedly be either dequeued or canceled.

Note: Some of this issue is already considered in #105

[e-backmark-ericsson]

Some of this was fixed in #126

We should try to fix the rest of it for 0.4