Publish Package Dialog UI Refresh #2 - #12206

Purpose

This PR cherry-picks changes made from PR #12171, since that was based off a custom branch.

This PR Updates the styling of PackagePublishView and introduces new optional fields as per the visual refresh design:

• The "Add Directory" button has been added, allowing a used to recursively add all files in a specific directory (and all subdirectories).
• The Package Contents list has been redesigned as a DataGrid.
• A new, optional Markdown Files Directory has been added.
• A 'More Details' expander section has been added with new, optional fields, such as license type.
• A clickable link to the MIT license has been added as per the new design.

Please Note: A follow-up PR will be needed to address the current discussion around loading/unloading DLLs. Current implementation of the Markdown functionality is setting a string property on the PublishPackageViewModel, the build process remains untouched for now.

Declarations

Check these if you believe they are true

• The codebase is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning and are documented in the API Changes document.
• This PR modifies some build requirements and the readme is updated

Reviewers

@QilongTang

FYIs

@Amoursol