[FR] Add WebApps support to project_management

Comienza en el paquete project_management y compara las API existentes de iOSApps y AndroidApps con el WebAppsService propuesto. Revisa el recurso webApps de la API REST de Firebase y determina la superficie completa de la API más allá de los metadatos y la configuración; se considera terminado cuando la compatibilidad con WebApps se expone de forma coherente con los servicios de plataforma existentes y está cubierta por las pruebas pertinentes.

Is your feature request related to a problem? Please describe.
The project_management package miss API to work with webApps resource

Describe the solution you'd like
API to work with WebApps similar to the ones available for iOSApps and AndroidApps

Describe alternatives you've considered
The single alternative I considered was to use the REST requests by hands

Additional context
I implemented a bare minimum solution just extending _ProjectManagementService

from firebase_admin import project_management


class WebApp:
    def __init__(self, app_id, service) -> None:
        self._app_id = app_id
        self._service = service

    @property
    def app_id(self):
        return self._app_id

    def get_metadata(self):
        return self._service.get_web_app_metadata(self._app_id)

    def get_config(self):
        return self._service.get_web_app_config(self._app_id)


class WebAppsService(project_management._ProjectManagementService):
    WEB_APPS_RESOURCE_NAME = 'webApps'

    def __init__(self, app):
        super().__init__(app)

    def list_web_apps(self) -> list[WebApp]:
        return self._list_apps(
            platform_resource_name=WebAppsService.WEB_APPS_RESOURCE_NAME,
            app_class=WebApp
        )

    def get_web_app_metadata(self, app_id):
        path = '/v1beta1/projects/-/{0}/{1}'.format(
            WebAppsService.WEB_APPS_RESOURCE_NAME,
            app_id,
        )
        return self._make_request('get', path)

    def get_web_app_config(self, app_id):
        path = '/v1beta1/projects/-/{0}/{1}/config'.format(
            WebAppsService.WEB_APPS_RESOURCE_NAME,
            app_id,
        )
        return self._make_request('get', path)

but it can be completed with all APIs