Add group_by to composite tool function (#1053)

[ormaq]

Related Issue(s):

Closes #1053

Proposed Changes:

For inclusion in changelog (if applicable):

1. Added group_by parameter to the composite_tool function to define grouping behavior.

Not intended for changelog:

1. Improved validation for group_by parameter values.

Diff of User Interface

Old behavior:

• No group_by option available for composite_tool.

New behavior:

• composite_tool now supports group_by with the following options:
  • "order": Creates a single composite output.
  • "strip_id": Creates multiple composites grouped by strip_id.

PR Checklist:

• This PR is as small and focused as possible.
• If this PR includes proposed changes for inclusion in the changelog, the title of this PR summarizes those changes and is ready for inclusion in the Changelog.
• I have updated docstrings for function changes and docs in the 'docs' folder for user interface / behavior changes.
• This PR does not break any examples or I have updated them.

(Optional) @mentions for Notifications:

[stephenhillier]

@ormaq thanks for opening a PR! The lint is failing due to formatting - it looks like it expects the new error string to be on its own line. I use yapf --in-place <file> for this (with yapf installed, of course). Let me know if you need help getting through the lint check.

In the meantime, I will ping somebody from the Orders API to have a quick look. Thanks again!

[ischneider]

While ValueError is semantically appropriate here (type is correct, value inappropriate), the pattern in this library is to use a ClientError.