Allow records as a header type and other basic types in the resource signature

[chamil321]

Purpose

Fixes ballerina-platform/ballerina-library#2699
Fixes ballerina-platform/ballerina-library#2807

Examples

Allow records as a header type

public type RateLimitHeaders record {|
    string x\-rate\-limit\-id;
    int x\-rate\-limit\-remaining;
    string[] x\-rate\-limit\-types;
|};

resource function get hello(@http:Header RateLimitHeaders rateLimitHeaders) returns string {
}

Support other basic types

    resource function get ofOtherPureHeaders(@http:Header int iid, @http:Header boolean bid,  
            @http:Header float[] faid, @http:Header decimal[] daid) returns json {
        //...
    }

Also types can be intersected with readonly type and be nilable

    resource function get ofOtherHeaderTypesWithReadonly(@http:Header readonly & int[] iaid,
            @http:Header readonly & float[]? faid) returns json {
        //...
     }

Checklist

• Linked to an issue
• Updated the changelog
• Added tests
• Updated the spec

[codecov]

Codecov Report

Merging #935 (9f5b2ac) into master (1c625a8) will decrease coverage by 0.04%.
The diff coverage is 83.92%.

@@             Coverage Diff              @@
##             master     #935      +/-   ##
============================================
- Coverage     80.67%   80.63%   -0.05%     
  Complexity       71       71              
============================================
  Files           347      348       +1     
  Lines         18674    18760      +86     
  Branches       4165     4183      +18     
============================================
+ Hits          15066    15127      +61     
- Misses         2803     2822      +19     
- Partials        805      811       +6     

Impacted Files	Coverage Δ
.../http/api/service/signature/HeaderRecordParam.java	74.28% <74.28%> (ø)
...ib/http/api/service/signature/AllHeaderParams.java	89.41% <81.25%> (-10.59%)	⬇️
...stdlib/http/api/service/signature/HeaderParam.java	84.74% <100.00%> (+5.57%)	⬆️
.../stdlib/http/api/service/signature/ParamUtils.java	86.84% <100.00%> (-1.26%)	⬇️
...mpl/listener/states/http2/ReceivingEntityBody.java	55.00% <0.00%> (-5.00%)	⬇️
...ontractimpl/listener/http2/Http2SourceHandler.java	88.88% <0.00%> (-2.78%)	⬇️
...transport/message/Http2InboundContentListener.java	51.28% <0.00%> (-2.57%)	⬇️
...nsport/contractimpl/DefaultHttpResponseFuture.java	74.07% <0.00%> (-1.24%)	⬇️
...ransport/message/DefaultFullHttpMessageFuture.java	96.00% <0.00%> (+4.00%)	⬆️

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