Offer variables for current try counter and maximum number of tries in Retry Instruction

Current Situation

• Users would like to check from an If Instruction or from a job if execution is repeated due to a Retry Instruction. This includes to make available
  • the maximum number of tries,
  • the current try counter.

Desired Behavior

• The following variables are provided:
  • js7MaxTries: indicates the maximum number of tries specified with the Retry Instruction.
    • The variable carries an empty value if an unlimited number of tries is specified with the Retry Instruction.
    • The variable is not defined when used outside of a {{Retry Instruction }}block. 
  • js7TryCount: indicates the counter of the current try within a Retry Instruction.
    • The variable carries the 0 value when used outside of a {{Retry Instruction }}block. 
• The variables can be used for example in an If Instruction and they can be mapped to environment variables for use with shell jobs.

Delimitation

• Variables related to a Retry Instruction are not related to the existing js7JobExecutionCount variable that counts the number of executions of a job for a given Order ID independently from the fact that a job is repeatedly executed due to user intervention (for example suspend/resume operations) or by automated behavior (Retry Instruction).