build_pkgdown_with_reports() : build a pkgdown with coverage and test reports

This function will generate the pkgdown of the current package using {pkgdown}, together with the {covr} and {testdown} reports. These reports will be embedded inside the pkgdown and accessible through the navigation bar. It requires the functions covr::report(), testdown::test_down, gitdown::git_down that are suggested package imports from {lozen}.

#' \dontrun{
# build_pkgdown_with_reports(
#    pkg = ".",
#    pkgdown_path = "public",
#    assets_path = "pkgdown/assets",
#    reports = c("testdown","coverage")
#' }