feat: add CourseModePriceRequested filter

[kiram15]

Description

This new filter determines the price a learner should be charged based upon their course mode. It has two related PRs that show the full implementation and how it is tested (see below).

This ticket is split from #338, please reference for previous PR comments.

Supporting information

https://2u-internal.atlassian.net/browse/ENT-11573
edx/edx-platform#365
openedx/edx-enterprise#2556

Testing instructions

Testing instruction in the edx-enterprise PR!

Checklists

Check off if complete or not applicable:

Merge Checklist:

• All reviewers approved
• Reviewer tested the code following the testing instructions
• CI build is green
• Changelog entry added using scriv with short description of the change
• Documentation updated (not only docstrings)
• Code dependencies reviewed
• Fixup commits are squashed away
• Unit tests added/updated
• Noted any: Concerns, dependencies, migration issues, deadlines, tickets

Post Merge:

• Trigger the release workflow to create a new GitHub release.
• Check new version is pushed to PyPI after tag-triggered build is finished.
• Delete working branch (if not needed anymore)
• Upgrade the package in the Open edX platform requirements (if applicable)

[kiram15]

Unrelated spelling change

[Copilot]

Pull request overview

Adds a new public filter to the openedx_filters.learning subdomain for determining the price a learner should be charged for a selected course mode, along with a basic passthrough test to validate default behavior when no pipeline is configured.

Changes:

• Added CourseModePriceRequested filter (org.openedx.learning.course_mode.price.requested.v1) with a run_filter(user, course_mode_data, price) API.
• Added a unit test verifying the filter returns the original inputs when no pipeline is configured.
• Fixed minor typos in an existing VerticalBlock-related docstring.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
openedx_filters/learning/filters.py	Introduces the new CourseModePriceRequested filter and corrects a docstring typo elsewhere in the module.
openedx_filters/learning/tests/test_filters.py	Adds a new test case covering the default passthrough behavior for the new filter.

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[pwnage101]

besides the minor assertion issue, this also still needs a version bump & changelog entry