feat: support range params in the policy

[jackcipher]

Add support for content-length-range in CreateBrowserBasedSignature

Background

The current implementation of CreateBrowserBasedSignature doesn't support specifying upload size limits in the policy. The content-length-range condition is a critical feature for controlling the size of uploaded objects, but it cannot be added directly as a map[string]string using the existing method.

Proposal

This pull request implements support for the content-length-range condition as described in the OBS API documentation:
https://support.huaweicloud.com/api-obs/obs_04_0012.html

Changes

1. Added a new ConditionRange struct to represent range conditions:

type ConditionRange struct {
    RangeName string
    Lower     int64
    Upper     int64
}

2. Modified the CreateBrowserBasedSignatureInput struct to include a slice of ConditionRange:

type CreateBrowserBasedSignatureInput struct {
    // ... existing fields
    RangeParams []ConditionRange
}

Usage

Users can now specify upload size limits when calling CreateBrowserBasedSignature:

input := &CreateBrowserBasedSignatureInput{
    Bucket:     "your-bucket",
    Key:        "your-key",
    Expires:    300,
    FormParams: map[string]string{"acl": "public-read"},
    RangeParams: []ConditionRange{
        {
            RangeName: "content-length-range",
            Lower:     1048576,  // 1MB
            Upper:     10485760, // 10MB
        },
    },
}

output, err := obsClient.CreateBrowserBasedSignature(input)