Feature/email subscription bug fixing

[lakesol]

Description

Upon testing I found a number issues with email subscriptions. This PR hopes to address the following issues;

Purpose

• Bugfix - Portal legal basis was not serialised correctly in some frameworks resulting in portal basis not being set via the API
• New feature - You can now apply legal basis to an individual subscription as well at the portal level. This is defined as optional parameters to avoid breaking changes.
• Bugfix - Corrected spelling mistake in SubscribeTo method parameters
• New feature - Return opt state, legal basis and legal basis explanation when getting email subscriptions for a contact
• Bugfix - UnsubscribeFrom was not removing subscriptions and was passing unneeded data in serialised API request
• New feature - SubscriptionLegalBasis and SubscriptionLegalBasisExplanation properties within SubscribeHubSpotModel have been marked as obsolete and new Portal* properties have been created to more closely match API specification and avoid confusion with subscription legal basis - This is a non breaking change.

[cdmdotnet]

Can you update the obsolete attribute to say which property to use instead. No issues with the implementation, just add a message so users know what to use as a replacement.

[cdmdotnet]

See conversation train

[lakesol]

Obsolete attribute updated