Description

Fix for list of base data convertion into Pandas DataFrame:

• This makes sure PandasConverter.GetDataFrame<T>(IEnumerable<T> data) doesn't assume the data is for a single symbol. For instance, if an option chain (IEnumerable<OptionUniverse>) is to be converted to a data frame, each item will correspond to a single symbol, that is, each contract.
• This is fixed generically so that a single list can hold data for multiple symbols, regardless of the number of items for each symbol contained in the list.

Related Issue

Closes #8331

Motivation and Context

Requires Documentation Change

How Has This Been Tested?

• Unit tests
• Regression algorithm

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• [ x My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>