Adds one or more key=value pairs as custom step or pipeline variables to a JSON payload that can be used to call the pipelines trigger API.
Multiple key=value pairs can be given in a single command or can be split across multiple commands.
If a key is added twice, the original value will be replaced.
Not currently supported in PowerShell
stepVariables: These key value pairs will be present in the environment of the triggered step
pipelineVariables: These key value pairs will be present in the environment of every step in the run that is triggered.