implement expression builders

[irina-herciu]

Add an expression builder for DynamoDB conditional expressions, akin to the Go SDK’s dynamodb/expression package and Boto3’s dynamodb.conditions, to streamline expression creation.

Description

In Document Model add support for fluent ExpressionBuilder similar to the GO SDK. The implementation will follow a design pattern comparable to the Go SDK's expression package, using method chaining to define update actions and condition expressions in a type-safe and readable way.

Create condition expressions examples:

Equal

//existing 
var conditionalExpression = new Expression
{
    ExpressionStatement = "#price = :price",
    ExpressionAttributeNames = { ["#price"] = "Price" },
    ExpressionAttributeValues = { [":price"] = 50 }
};

//build 
var expression = ConditionExpressionBuilder.New().WithName("Price").Equal(50).Build();

And

//existing 
var conditionalExpression = new Expression
                    {
                        ExpressionStatement = "attribute_not_exists(#id) AND #price <> :price",
                        ExpressionAttributeNames = { ["#id"] = "Id", ["#price"] = "Price" },
                        ExpressionAttributeValues = { [":price"] = 500 }
                    };

//build 
var expression = ConditionExpressionBuilder.New().WithName("Id").AttributeExists().
                And(ConditionExpressionBuilder.New().WithName("Price").Equal(50)).Build();

Update actions expression:

Set

//existing 
var updateExpression = new Expression
{
    ExpressionStatement = "SET #garbage = :garbage",
    ExpressionAttributeNames = { ["#garbage"] = "Garbage" },
    ExpressionAttributeValues = { [":garbage"] = "asdf" }
};

//build 
var expression = UpdateExpressionBuilder.New().
    Set(NameBuilder.New("Garbage"), SetValueBuilder.New().WithValue("asdf")).Build();

Set increment

//existing 
var updateExpression = new Expression
{
    ExpressionStatement = "SET #price = #price + :inc",
    ExpressionAttributeNames = { ["#price"] = "Price" },
    ExpressionAttributeValues = { [":inc"] = 1 }
}

//build 
var expression = UpdateExpressionBuilder.New().
    Set(NameBuilder.New("Price"), SetValueBuilder.New().WithName("Price").Plus(1))
    .Build(); 

Motivation and Context

#2602

Testing

Unit tests added

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license