Move node selection logic in a package

[raju249]

Thanks for contributing to Selenium!
A PR well described will help maintainers to quickly review and merge it

Description

This PR separates the tightly coupled logic of nodeSelection to run a session, into a separate package and can be independently modified going forward. It doesn't and should not change any functionality from previoud build and should not show any differences for the user to run a session.

Motivation and Context

1. There is work going on adding support for RedisDistributor for which this same nodeSelection Package would be used/modified to make it work with redis backed distributor.
2. Hence as a first step in MVP and not have too may changes in RedisDistributor PR, this PR will make that change and I would iterate from there after it is merged.
3. The GridModel class stores the nodes and listens to addition and removal of Nodes. The NodeSelector class will help us select the node from the pool of nodes. Now, this pool of the nodes can be an in-memory hash map for a local distributor, it can also be a redis backed store for RedisBasedDistributor or a database backed store for JdbcBackedDistributor

The changes to make the datastore configurable inside the NodeSelector class will be done in #8403

Types of changes

• [-] 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)

Checklist

• I have read the contributing document.
• [-] My change requires a change to the documentation.
• [-] I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[diemol]

@raju249
Could you please add some context to the PR? The PR template is being completely ignored.
How can this be tested? Why are these changes made?

[raju249]

Hey @diemol I have updated the PR description. Please take a look. Thanks 🙇

[shs96c]

I suspect that what we want to do is to ensure that the model is immutable, and a snapshot of the understood state of the system at the time it's created. It's also just a model, so there's no need to have things like Host.runHealthCheck

[AutomatedTester]

I believe all comments have been addressed and will merge on Tuesday morning

@shs96c @diemol

[diemol]

@raju249 I made the changes we spoke about. Please have a look, and if you are ok with them, we can merge this. Thanks!

[raju249]

Thanks much @diemol 🙇

Changes LGTM. 👍

We can land this.