Add Ramble application and experiment definitions

[healpert]

Overview

Write an explanation of the PR's goal here.

✨ Change Description/Rationale

• ➕ Added Ramble application.py definition
• Add benchmark experiment.py definition
• Add documentation to get started with ramble
• Added example python script to run an experiment

If a longer explanation is required, it goes in paragraphs below the title sentence.

👀 Reviewer Checklist

• All GitHub actions and runners have passed if applicable
• Commits are clean and relevant

✅ PR Checklist

• Remove or update the template boilerplate text
• Commits are relevant and combined where appropriate
• Rebase off spatter-devel
• Reviewers Requested
• Projects associated
• Commits mention issue and/or PR numbers at the bottom of the message
• Relevant issues are linked into the PR
• TODOs are completed
• Reviewer checklist is updated

🚀 TODOs

• Add items to this TODO list that shouldn't be forgotten, or that reviewers have requested that you complete.

📌 Future Work

• Use this section to document the related work that you are not doing.
• Documenting Future Work and explanations will help reviewers understand why those things are not being completed in this PR.

[jyoung3131]

Eric noted that one script update will be to add numthreads setting for Ramble which supersedes nthread setting for Spatter.

[jyoung3131]

Made some changes to README to clarify the process of testing locally with Ramble.