[New Feature] Support for creating maps with Query expressions

[SandaruJayawardana]

Related Spec Issue - ballerina-platform/ballerina-spec#710
Lang Issue - #36193

Currently compiler supports for creating tables and streams with query expressions. With this feature, maps also can be created with query expressions.

Ex. Creating a map from a table.

type Employee record {|
    readonly int id;
    string firstName;
    int salary;
|};

public function main() {
    Employee[] employees2 = [
        {id: 1, firstName: "John", salary: 80},
        {id: 2, firstName: "Jane", salary: 150}
    ];

    var m1 = map from var e in employees2 // Add `map` as the query-construct-type
                    where e.salary >= 100
                    select [e.id.toString(), e];

    // m1 => {"2": {id: 2, firstName: "Jane", salary: 150}}

}

Proposed changes for this new feature,

1. Modify the parser to allow map as a query-construct-type.
2. Implement type checking logic in TypeChecker
3. Implement desugaring logic
4. Introduce helper function to create maps in helper.bal

Highly appreciate your input on this discussion.

[SandaruJayawardana]

PR for Parser changes - #36304