Prompt token replacement alternative solution

[codingbandit]

Prompt token replacement alternative solution

Details on the issue fix or feature implementation

Defines well known tokens and replaces those values in the prompt prefix and suffix during the loading of an agent.

Confirm the following

• I started this PR by branching from the head of the default branch
• I have targeted the PR to merge into the default branch
• This PR needs to be cherry-picked into at least one release branch
• I have included unit tests for the issue/feature
• I have included inline docs for my changes, where applicable
• I have successfully run a local build
• I have provided the required update scripts, where applicable
• I have updated relevant docs, where applicable