chore(middleware/tracing): upgrade otel semconv

[flc1125]

Description (what this PR does / why we need it):

Upgrade otel semconv

https://github.com/open-telemetry/opentelemetry-specification/blob/v1.24.0/specification/trace/semantic_conventions/http.md

[flc1125]

或者整个v2版本：github.com/go-kratos/kratos/v2/middleware/tracing/v2，增加一些自定义的设定span补充的逻辑？

@shenqidebaozi

草稿版：

package v2

import (
	"context"

	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/trace"

	"github.com/go-kratos/kratos/v2/middleware"
)

var defaultPropagator = propagation.NewCompositeTextMapPropagator(Metadata{}, propagation.Baggage{}, propagation.TraceContext{})

type Handler interface {
	Start(ctx context.Context, req interface{}, span trace.Span) context.Context
	End(ctx context.Context, span trace.Span, reply interface{}, err error)
}

type Tracer struct {
	tracerName     string
	spanKind       trace.SpanKind
	tracerProvider trace.TracerProvider
	propagator     propagation.TextMapPropagator
	handlers       []Handler
}

type Option func(*Tracer)

func WithTracerProvider(provider trace.TracerProvider) Option {
	return func(t *Tracer) {
		t.tracerProvider = provider
	}
}

func WithTracerName(name string) Option {
	return func(t *Tracer) {
		t.tracerName = name
	}
}

func WithSpanKind(kind trace.SpanKind) Option {
	return func(t *Tracer) {
		t.spanKind = kind
	}
}

func WithPropagator(propagator propagation.TextMapPropagator) Option {
	return func(t *Tracer) {
		t.propagator = propagator
	}
}

func WithHandlers(handlers ...Handler) Option {
	return func(t *Tracer) {
		t.handlers = append(t.handlers, handlers...)
	}
}

func WithOptions(opts ...Option) Option {
	return func(t *Tracer) {
		for _, o := range opts {
			o(t)
		}
	}
}

func NewTracer(opts ...Option) *Tracer {
	t := &Tracer{
		tracerName:     "kratos",
		spanKind:       trace.SpanKindInternal,
		tracerProvider: otel.GetTracerProvider(),
		propagator:     defaultPropagator,
		handlers: []Handler{
			DefaultHandler, // default handler
		},
	}
	return t
}

func (t *Tracer) Start(ctx context.Context, req interface{}) (context.Context, trace.Span) {
	ctx, span := t.tracerProvider.Tracer(t.tracerName).Start(ctx, "", trace.WithSpanKind(t.spanKind))
	for _, h := range t.handlers {
		h.Start(ctx, req, span)
	}
	return ctx, span
}

func (t *Tracer) End(ctx context.Context, span trace.Span, reply interface{}, err error) {
	for _, h := range t.handlers {
		h.End(ctx, span, reply, err)
	}
}

func Server(opts ...Option) middleware.Middleware {
	tracer := NewTracer(
		WithTracerName("kratos"),
		WithSpanKind(trace.SpanKindServer),
		WithOptions(opts...),
	)
	return func(handler middleware.Handler) middleware.Handler {
		return func(ctx context.Context, req interface{}) (reply interface{}, err error) {
			ctx, span := tracer.Start(ctx, req)
			defer func() { tracer.End(ctx, span, reply, err) }()
			return handler(ctx, req)
		}
	}
}

[shenqidebaozi]

There is no need to add V2 version

[shenqidebaozi]

Retention is only to avoid affecting the query configuration that users have already used

[flc1125]

Retention is only to avoid affecting the query configuration that users have already used

OK。后面我在研究看看，如何在当前版本下，支持增加自定义处理 Handler 的支持。接口按如下定义OK没：

type Handler interface {
	Start(ctx context.Context, span trace.Span, req interface{}) context.Context
	End(ctx context.Context, span trace.Span, reply interface{}, err error) context.Context
}