Change get_data() to always return a long form data frame with dimension IDs.

[aaronweeden]

WORK IN PROGRESS

Description

This PR changes the get_data() method to always return a long form data frame and to include the dimension IDs in the data. For example, given this call to get_data():

with dw:
    df = dw.get_data(
        duration=('2024-01-01', '2024-01-02'),
        realm='Jobs',
        metric='Number of Jobs Ended',
        dimension='Service Provider',
        dataset_type='timeseries',
        aggregation_unit='Day',
        filters={
            'Service Provider': ('PSC', 'SDSC', 'NCSA'),
        },
    )

The df variable will be assigned this data frame:

	Date	Metric	Service Provider ID	Service Provider Label	Value
0	2024-01-01	Number of Jobs Ended	848	PSC	16146
1	2024-01-01	Number of Jobs Ended	856	SDSC	8450
2	2024-01-01	Number of Jobs Ended	844	NCSA	2650
3	2024-01-02	Number of Jobs Ended	848	PSC	11702
4	2024-01-02	Number of Jobs Ended	856	SDSC	7413
5	2024-01-02	Number of Jobs Ended	844	NCSA	2497

Motivation and Context

Long form data are easier to process and plot.

Also, currently, sometimes data is returned as a Series instead of a DataFrame, which is difficult to work with because it often requires casting the Series as a DataFrame.

The dimension IDs are needed because labels are not necessarily unique (e.g., two people can have the same name).

This PR will also be a basis for allowing multiple metrics to be requested and returned in the same data frame (which will be a separate PR) and multiple data about the dimension to be included in the data frame (#35).

Tests performed

Types of changes

• Refactoring / documentation update (non-breaking change which does not change functionality)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Release preparation

Checklist:

• CHANGELOG.md has been updated
• The milestone is set correctly on the pull request
• The appropriate labels have been added to the pull request
• Running the automated tests (see docs/developing.md) produces no errors
• Updates have been made to the xdmod-notebooks repository as necessary, and the notebooks all run successfully