Add contextually expected type inference support for client methods

[chamil321]

Purpose

Fixes ballerina-platform/ballerina-library#1371

Examples

json j = check clientEndpoint->post("/test", request);

Checklist

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

[codecov]

Codecov Report

Merging #396 (0f0ef0c) into master (5bb56a7) will decrease coverage by 0.03%.
The diff coverage is 66.66%.

@@             Coverage Diff              @@
##             master     #396      +/-   ##
============================================
- Coverage     76.89%   76.86%   -0.04%     
  Complexity       62       62              
============================================
  Files           319      319              
  Lines         16258    16258              
  Branches       3735     3735              
============================================
- Hits          12501    12496       -5     
- Misses         3044     3048       +4     
- Partials        713      714       +1     

Impacted Files	Coverage Δ	Complexity Δ
http-ballerina/resiliency_failover_client.bal	82.55% <37.50%> (-0.68%)	0.00 <0.00> (ø)
http-ballerina/resiliency_load_balance_client.bal	89.22% <50.00%> (-0.60%)	0.00 <0.00> (ø)
http-ballerina/http_client_endpoint.bal	85.76% <100.00%> (ø)	0.00 <0.00> (ø)
http-ballerina/http_client_object.bal	100.00% <100.00%> (ø)	0.00 <0.00> (ø)
...sport/message/ClientRemoteFlowControlListener.java	52.63% <0.00%> (-15.79%)	0.00% <0.00%> (ø%)
...ansport/message/DefaultBackPressureObservable.java	64.28% <0.00%> (-7.15%)	0.00% <0.00%> (ø%)
...tractimpl/sender/ConnectionAvailabilityFuture.java	70.73% <0.00%> (-2.44%)	0.00% <0.00%> (ø%)
...alang/net/http/service/signature/ParamHandler.java	86.02% <0.00%> (-1.48%)	0.00% <0.00%> (ø%)
...nsport/contractimpl/DefaultHttpResponseFuture.java	77.27% <0.00%> (+3.89%)	0.00% <0.00%> (ø%)

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