Use context aware functions instead of deprecated Read, Update, Delete, etc.

[amhn]

Summary

In schema.Resource currently the deprecated Create, Read, Update, Delete fields are used. Replacing them with the
context aware functions will allow terraform to cancel requests and the functions can use the logging functions provided by the SDK.
See https://learn.hashicorp.com/tutorials/terraform/provider-debug?in=terraform/providers#add-warning-message.

Example

https://learn.hashicorp.com/tutorials/terraform/provider-debug?in=terraform/providers#add-warning-message

Usage

Helps the developer debugging and allows showing warning messages to the user.