Remove Instance::get_proxy() and Instance::get_cainfo().

We can't get the values that were set using environment variables or build-time
options. We don't need them anymore for initializing “Connection”s.

include/instance.hpp

@@ -150,19 +150,6 @@ public:
         CURLWrapper::set_proxy(proxy);
     }
 
-    /*!
-     *  @brief  Returns the proxy string that was previously set.
-     *
-     *  Does not return the proxy if it was set from an environment variable.
-     *
-     *  @since  0.1.0
-     */
-    [[nodiscard]]
-    string_view get_proxy() const noexcept
-    {
-        return _proxy;
-    }
-
     /*!
      *  @brief  Returns the NodeInfo of the instance.
      *
@@ -202,18 +189,6 @@ public:
         CURLWrapper::set_cainfo(path);
     }
 
-    /*!
-     *  @brief  Returns the cainfo path that was previously set.
-     *
-     *  This is used when initializing a Connection.
-     *
-     *  @since  0.3.0
-     */
-    string_view get_cainfo() const noexcept
-    {
-        return _cainfo;
-    }
-
     void set_useragent(const string_view useragent)
     {
         _useragent = useragent;