Allow Custom Span Name

[Quaqmre]

Feature Request: Allow Custom Span Name Generation in before Hook

I have implemented a change that allows dynamic span name generation in the before hook of otelPlugin.

Currently, before sets spanName statically:

func (p *otelPlugin) before(spanName string) gormHookFunc {
    return func(tx *gorm.DB) {
        tx.Statement.Context, _ = p.tracer.Start(tx.Statement.Context, spanName, trace.WithSpanKind(trace.SpanKindClient))
    }
}

I modified it to accept a function parameter for dynamic span naming:

func (p *otelPlugin) before(spanNameFunc func(string) string) gormHookFunc {
    return func(tx *gorm.DB) {
        spanName := spanNameFunc(tx.Statement.Table) // Example usage
        tx.Statement.Context, _ = p.tracer.Start(tx.Statement.Context, spanName, trace.WithSpanKind(trace.SpanKindClient))
    }
}

This provides more flexibility by allowing users to customize span names based on runtime context.

Motivation
Enables dynamic span naming based on table names, operations, or other context-specific factors.
Improves trace readability and debugging.
Such as i want to set name as caller method name.
Provides a more flexible API for observability use cases.
Next Steps
If this feature is accepted, I would like to open a PR with my implementation. Please let me know if this approach aligns with the project's goals.