Add the ability to use Routes::bind with constant member functions

[tyler92]

There was a compile error with the following scenario:

class MyHttpServer
{
    // ...
    void run()
    {
        using namespace Pistache::Rest;
        Routes::Get(router, "/ping", Routes::bind(&MyHttpServer::requestHandler, this));
    }
    
    void requestHandler(const Pistache::Rest::Request& request,
                        Pistache::Http::ResponseWriter response) const
    {
        response.send(Pistache::Http::Code::Ok, "OK");
    }
    
    // ...
};

Compiler output:

main.cpp:38: error: no matching function for call to ‘bind(void (MyHttpServer::*)(const Pistache::Rest::Request&, Pistache::Http::ResponseWriter) const, MyHttpServer*)’
main.cpp: In member function ‘void MyHttpServer::run()’:
main.cpp:38:58: error: no matching function for call to ‘bind(void (MyHttpServer::*)(const Pistache::Rest::Request&, Pistache::Http::ResponseWriter) const, MyHttpServer*)’
   38 |                 Routes::Get(router, "/ping", Routes::bind(&MyHttpServer::requestHandler, this));
      |    

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.04 🎉

Comparison is base (7f6bb27) 78.45% compared to head (675b6f0) 78.49%.

❗ Current head 675b6f0 differs from pull request most recent head fa6e5da. Consider uploading reports for the commit fa6e5da to get more accurate results

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1127      +/-   ##
==========================================
+ Coverage   78.45%   78.49%   +0.04%     
==========================================
  Files          53       53              
  Lines        6879     6892      +13     
==========================================
+ Hits         5397     5410      +13     
  Misses       1482     1482              

Impacted Files	Coverage Δ
include/pistache/router.h	100.00% <100.00%> (ø)

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[dennisjenkins75]

LGTM. Thank you for the contribution.

[kiplingw]

@Tachi107, if you're fine with it too, I'll merge.

[Tachi107]

Thanks for the patch! Looks good to me as well