Added GitHubActionsVirtualEnvs

The generators will create GitHub Actions scripts which will set
the environment for the next steps.

Usage as follows in the commandline:

```yml
- name: Conan install
  run: conan install . -g GitHubActionsVirtualRunEnv
- name: Activate env
  run: <conan_generator_dir>/activate_github_actions_runenv.sh
- name:
  run: echo $PATH
```

Contributes to CURA-9177_Fix_CI_CD

generators/GitHubActionsBuildEnv.py

@@ -0,0 +1,27 @@
+from pathlib import Path
+
+from jinja2 import Template
+
+from conan.tools.env import VirtualBuildEnv
+from conans.model import Generator
+
+
+class GitHubActionsBuildEnv(Generator):
+
+    @property
+    def filename(self):
+        filepath = str(Path(self.conanfile.generators_folder).joinpath("activate_github_actions_buildenv"))
+        if self.conanfile.settings.get_safe("os") == "Windows":
+            if self.conanfile.conf.get("tools.env.virtualenv:powershell", check_type = bool):
+                filepath += ".ps1"
+            else:
+                filepath += ".bat"
+        else:
+            filepath += ".sh"
+        return filepath
+
+    @property
+    def content(self):
+        template = Template("""{% for k, v in envvars.items() %}echo "{{ k }}={{ v }}" >> $GITHUB_ENV\n{% endfor %}""")
+        envvars = self.conanfile.buildenv_info.vars(self.conanfile)
+        return template.render(envvars = envvars)

generators/GitHubActionsRunEnv.py

@@ -0,0 +1,27 @@
+from pathlib import Path
+
+from jinja2 import Template
+
+from conan.tools.env import VirtualRunEnv
+from conans.model import Generator
+
+
+class GitHubActionsRunEnv(Generator):
+
+    @property
+    def filename(self):
+        filepath = str(Path(self.conanfile.generators_folder).joinpath("activate_github_actions_runenv"))
+        if self.conanfile.settings.get_safe("os") == "Windows":
+            if self.conanfile.conf.get("tools.env.virtualenv:powershell", check_type = bool):
+                filepath += ".ps1"
+            else:
+                filepath += ".bat"
+        else:
+            filepath += ".sh"
+        return filepath
+
+    @property
+    def content(self):
+        template = Template("""{% for k, v in envvars.items() %}echo "{{ k }}={{ v }}" >> $GITHUB_ENV\n{% endfor %}""")
+        envvars = self.conanfile.runenv_info.vars(self.conanfile, scope = "run")
+        return template.render(envvars = envvars)