Rename methods.

[aaronweeden]

WORK IN PROGRESS

Description

This PR renames the following methods.

Old name	New name
describe_realms	get_realm_metadata
describe_metrics	get_metric_metadata
describe_dimensions	get_dimension_metadata
describe_raw_realms	get_raw_realm_metadata
describe_raw_fields	get_raw_field_metadata
get_filter_values	get_dimension_data

The old method names will still work but are given deprecation warnings.

Motivation and Context

The goal is to use more consistent and specific method names.

We got feedback that it's hard to keep track of which methods start with describe and which start with get.

get_filter_values is renamed to get_dimension_data since these data will also be useful outside the context of filtering, especially with #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