Explore introducing builder-pattern to event creation

[tyiu]

Many different kinds of Nostr events have overlap in how it is constructed, including semantic meaning of certain tags.

The current pattern of having one distinct creation function in the EventCreating protocol per kind makes it difficult to promote code sharing in the implementation.

For the developer who would be using Nostr SDK, it may be difficult to use the SDK to create events. It may make it harder for them to write maintainable or DRY (don't repeat yourself) code.

Let's explore if it's possible to use a builder pattern to solve these problems.