Restructure DA classes

[shorvath-noaa]

Restructure the formulation of DataAssimilation object. Instead of using Abstract Classes, this creates a series of base classes for each type of data assimilation (streamflow nudging, reservoir persistence, and reservoir RFC). A child class then inherits methods all three of these base classes then turns on/off DA features based on user input from the configuration file.

The individual base classes can also be used with the future implementation of a separate reservoir module. For instance, for a single persistence reservoir, we can just use the PersistenceDA() class and skip all of the code/methods associated with streamflow nudging and RFC.

I've also added a method of initializing a DataAssimilation object without reading DA data from files as will be needed for BMI compatibility.

Additions

• Base class objects NudgingDA, PersistenceDA, RFCDA
• Child class that inherits methods from all base classes and turns features on/off based on user input in config file

Removals

• Abstract Class methods

Changes

Testing

Screenshots

Notes

Todos

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Visually tested in supported browsers and devices (see checklist below 👇)
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist

Target Environment support

• Windows
• Linux
• Browser

Accessibility

• Keyboard friendly
• Screen reader friendly

Other

• Is useable without CSS
• Is useable without JS
• Flexible from small to large screens
• No linting errors or warnings
• JavaScript tests are passing

[kumdonoaa]

This PR greatly enhances code readability and efficiency. Great job.