Add support for custom remote function mapping via Annotation

[chathushkaayash]

Purpose

$subject

Resolves Support Custom Remote Function Mapping via Annotation

Examples

service class WsService {
    *websocket:Service;

    @websocket:DispatcherMapping {
        value: "subscribe"
    }
    remote function onSubscribeMessage(Subscribe message) returns string {
        return "Subscribed";
    }
}

Checklist

• Linked to an issue
• Updated the specification
• Updated the changelog
• Added tests
• Checked native-image compatibility

[codecov]

Codecov Report

Attention: Patch coverage is 97.72727% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.42%. Comparing base (3a3f729) to head (7105638).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...o/ballerina/stdlib/websocket/WebSocketService.java	95.23%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1553   +/-   ##
=========================================
  Coverage     82.41%   82.42%           
- Complexity      599      601    +2     
=========================================
  Files            48       48           
  Lines          3111     3123   +12     
  Branches        414      414           
=========================================
+ Hits           2564     2574   +10     
- Misses          400      402    +2     
  Partials        147      147           

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[ThisaruGuruge]

Please check the Sonar analysis and whether we can fix the duplication warning.

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[ThisaruGuruge]

This is okay, but ideally, we should check this on function symbol. Can do something like this:

The reasons are follows;

There are two main APIs we use in compiler plugins;

• Syntax API
• Semantic API

Semantic API is more convenient and robust when it comes to validations IMO, because it exposes the semantic model instead of the raw syntax tree. When we use the Syntax API in compiler plugins to validate code, it takes more effort as we have to rely on string manipulations, string concatenations, etc., where semantic API provides more easy-to-use APIs for validation. (Of course there are instances where we have to use syntax APIs, and this is not to discourage the use of syntax API, but in the scenarios like these, it would be better to use Semantic API).

    FunctionSymbol functionSymbol = // Get the node from the semantic model
    if (!functionSymbol.qualifiers.contains(Qualifier.REMOTE) {
        continue;
    }

[ThisaruGuruge]

Added a minor comment, but LGTM