Fix IParamConverter not being applied to IDictionary parameter values

[Copilot]

The RequestHandler.GetParams() method was not using the IParamConverter system for values within IDictionary parameters, causing inconsistent behavior compared to individual parameters. This was particularly problematic for DateTime values, which should be converted to ISO8601/RFC3339 format.

Problem

When using dictionary parameters with QueryParam, FormParam, or HeaderParam attributes, the values were converted using direct .ToString() calls instead of the configured parameter converters:

// Before fix - DateTime gets locale-specific format
var queryParams = new Dictionary<string, object>
{
    ["startDate"] = new DateTime(2023, 12, 25, 14, 30, 45, DateTimeKind.Utc)
};
// Results in: startDate=12/25/2023 2:30:45 PM (locale-dependent)

// Individual DateTime parameters worked correctly using DateTimeIso8601ParamConverter
public Task GetData([QueryParam] DateTime startDate) // Uses ISO8601 format

Solution

1. Extended IParamConverterManager with a new GetConverter(Type type) method to support type-based converter lookup
2. Updated ParamConverterManager to implement the new method using existing converter logic
3. Modified RequestHandler.GetParams() to use a new ConvertValueToString() helper that leverages the param converter system for dictionary values
4. Added comprehensive tests covering various dictionary types with DateTime values

Changes Made

• Added GetConverter(Type type) to IParamConverterManager interface
• Implemented the method in ParamConverterManager with minimal TypeOnlyParameterInfo helper class
• Created ConvertValueToString() helper method in RequestHandler
• Updated dictionary value handling in QueryParam, FormParam, and HeaderParam processing
• Added 5 new tests covering IDictionary, Dictionary<string,object>, Dictionary<string,DateTime>, and Hashtable scenarios

Result

Dictionary parameters now consistently use the same conversion logic as individual parameters:

var queryParams = new Dictionary<string, object>
{
    ["startDate"] = new DateTime(2023, 12, 25, 14, 30, 45, DateTimeKind.Utc)
};
// Now results in: startDate=2023-12-25T14:30:45.0000000Z (ISO8601 format)

All existing tests continue to pass, ensuring backward compatibility while fixing the inconsistency.

Fixes #91.

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[twogood]

Change IParamConverter.CanConvert() to take a Type instead of creating a fake ParameterInfo instance.

[twogood]

@copilot please Change IParamConverter.CanConvert() to take a Type instead of creating a fake ParameterInfo instance in ParamConverterManager

[Copilot]

Changed IParamConverter.CanConvert() to take Type instead of ParameterInfo and removed the TypeOnlyParameterInfo helper class. All implementations now use Type directly, making the code cleaner and eliminating the fake ParameterInfo instances. Commit: 1bff500