Add key encoding

[caleblloyd]

Add Key Encoding to conform with the rules of NATS KV Keys

[Copilot]

Pull Request Overview

This PR introduces key encoding functionality to ensure keys conform with NATS KV key rules. The key changes include:

• Adding a new key encoder implementation (NatsCacheKeyEncoder) with corresponding unit tests.
• Updating NatsCache and its extension registration to utilize the new key encoder.
• Adjusting logging and error handling in key operations.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/UnitTests/KeyEncoder/NatsCacheKeyEncoderTest.cs	Adds comprehensive tests for key encoding and decoding.
src/NatsDistributedCache/NatsDistributedCacheExtensions.cs	Updates dependency injection to include the key encoder service.
src/NatsDistributedCache/NatsCacheKeyEncoder.cs	Implements the new key encoder that transforms keys to KV-legal forms.
src/NatsDistributedCache/NatsCache.cs	Refactors key construction to use the encoded key and removes retry logic.
src/NatsDistributedCache/NatsCache.Log.cs	Adjusts logging events and removes the update failure logging.
src/NatsDistributedCache/INatsCacheKeyEncoder.cs	Defines the interface for the new key encoder.

Comments suppressed due to low confidence (1)

src/NatsDistributedCache/NatsCache.cs:259

• The removal of the retry mechanism for handling NatsKVWrongLastRevisionException in GetAndRefreshAsync may impact optimistic concurrency behavior. Consider verifying if this behavior change is intentional or reintroducing a retry strategy to maintain data consistency under concurrent updates.

private async Task<byte[]?> GetAndRefreshAsync(string key, CancellationToken token)