update to latest gradle version and add gradle wrapper

[Joseph5610]

Hello,

While we tried to use the allure-server tool, we discovered that it is build with rather old version of gradle.
This PR updates the gradle version to 8.7. With that, the gradle docker image in the Dockerfile is updated as well as the github actions used to build the project.

For some specific reason, this repo excluded the gradle wrapper from the VCS. While updating the gradle github action, I found out that the wrapper is now the preferred way how to work with it. For this reason, I removed required wrapper files from gitignore. Even the gradle team itself recommends that the wrapper files are so small so they should be committed into the repo - https://docs.gradle.org/current/userguide/gradle_wrapper.html#sec:adding_wrapper so I don´t expect it will cause any problems, on the contrary, the presence of gradle wrapper files in the VCS can simplify the first load of the project.