使用平板点分隔键新建文本编码器,以提高可读性和性能

Describe the problem you'd like to solve
Your feature request is related to a problem? Please describe.
Zap's current encoders (JSON, console) don't provide an easy-to-read text output for nested objects:

• JSONEncoder is structured but verbose and less operator-friendly for quick inspection in terminals.
• ConsoleEncoder is compact but does not handle nested objects in a way that makes them easy to grep or read.
• Alternatives like Kubernetes’ klog textlogger and Go's slog.TextHandler provide text output, but are either slower or less flexible.

Describe the solution you'd like
Introduce a new zapcore.Encoder implementation (e.g., TextEncoder) with the following features:

1. Dot-flattened keys for nested objects
   Example:

logger.Info("user created", zap.Any("user", User{
  Name: "Alice",
  Addr: Addr{City: "Bangalore", Zip: "560001"},
}))

Current JSONEncoder output:

{"user": {"Name": "Alice", "Addr": {"City": "Bangalore", "Zip": "560001"}}}

Proposed TextEncoder output:

"user.Name"="Alice" "user.Addr.City"="Bangalore" "user.Addr.Zip"="560001"

This makes logs more human-readable and grep-friendly.
2. Performance improvements
Benchmarks show this encoder is faster than both k8s textlogger and slog.TextHandler, while competitive with zap’s json encoder.
3. Seamless zap integration

• Provided as a zapcore.Encoder implementation.
• Configurable via zapcore.NewTextEncoder(cfg) or zap configuration.

Describe alternatives you've considered

• Using JSONEncoder → too verbose and not grep-friendly.
• Using ConsoleEncoder → compact but nested structures are still hard to scan.
• Using Kubernetes’ klog textlogger / slog.TextHandler → slower and not integrated with zap.

Is this a breaking change?
No. This would be an additive change introducing a new encoder.
Existing users of JSONEncoder and ConsoleEncoder remain unaffected.

Additional context

• Prototype implementation: GitHub.com/sagarsuperuser/zap/tree/text-encoder
• Includes tests, benchmarks (https://GitHub.com/sagarsuperuser/zap/tree/text-encoder/benchmarks)
• Benchmarks :

Log a message and 10 fields

(https://GitHub.com/sagarsuperuser/zap/tree/text-encoder#log-a-message-and-10-fields)