build(tgbot-gen): Changes and additions required to generate the API client with auth (cookie)

I use a standard set of templates, changes are made in api-header.mustache and api-source.mustache. Their _old versions contain the originals. Additions are necessary for the header argument in the generated functions so that you can authenticate using cookies.

api/_build/my-cpp-templates/cpp-restsdk/README.mustache

@@ -0,0 +1,59 @@
+# C++ API client
+
+{{#appDescriptionWithNewLines}}
+{{{.}}}
+{{/appDescriptionWithNewLines}}
+
+## Overview
+This API client was generated by the [OpenAPI Generator](https://openapi-generator.tech) project. By using the [OpenAPI spec](https://openapis.org) from a remote server, you can easily generate an API client.
+
+- API version: {{appVersion}}
+- Package version: {{packageVersion}}
+{{^hideGenerationTimestamp}}
+- Build date: {{generatedDate}}
+{{/hideGenerationTimestamp}}
+- Generator version: {{generatorVersion}}
+- Build package: {{generatorClass}}
+{{#infoUrl}}
+For more information, please visit [{{{infoUrl}}}]({{{infoUrl}}})
+{{/infoUrl}}
+
+- API namespace: {{{apiPackage}}}
+- Model namespace: {{{modelPackage}}}
+
+## Installation
+
+### Prerequisites
+
+Install [cpprestsdk](https://github.com/Microsoft/cpprestsdk).
+
+- Windows: `vcpkg install cpprestsdk cpprestsdk:x64-windows boost-uuid boost-uuid:x64-windows`
+- Mac: `brew install cpprestsdk`
+- Linux: `sudo apt-get install libcpprest-dev`
+
+### Build
+
+```sh
+cmake -DCPPREST_ROOT=/usr -DCMAKE_CXX_FLAGS="-I/usr/local/opt/openssl/include" -DCMAKE_MODULE_LINKER_FLAGS="-L/usr/local/opt/openssl/lib"
+make
+```
+
+### Build on Windows with Visual Studio (VS2017)
+
+- Right click on folder containing source code
+- Select 'Open in visual studio'
+- Once visual studio opens, CMake should show up in top menu bar.
+- Select CMake > Build All.
+
+*Note: If the CMake menu item doesn't show up in Visual Studio, CMake
+for Visual Studio must be installed. In this case, open the 'Visual Studio
+Installer' application. Select 'modify' Visual Studio 2017. Make sure
+'Desktop Development with C++' is installed, and specifically that 'Visual
+C++ tools for CMake' is selected in the 'Installation Details' section.
+
+Also be sure to review the CMakeLists.txt file. Edits are likely required.*
+
+## Author
+
+{{#apiInfo}}{{#apis}}{{#-last}}{{infoEmail}}
+{{/-last}}{{/apis}}{{/apiInfo}}