[BUG] Get-PnPSiteTemplate - exporting SiteHeader and SiteFooter

When I export a PnP Provisioning template with Get-PnPSiteTemplate and have the SiteHeader handler specified in the config JSON, I get this short section:

      <pnp:Header Layout="Extended" MenuStyle="MegaMenu" ShowSiteTitle="false" />

The section doesn't include other important "modern" settings, like background image.

Ditto SiteFooter

      <pnp:Footer Enabled="true" RemoveExistingNodes="false" BackgroundEmphasis="Strong" />

I use a fix like this after applying the template:

# # Set site header background image and other settings
Set-PnPWebHeader -Connection $newSiteConnection `
    -HeaderLayout Extended `
    -HeaderBackgroundImageUrl "/sites/$siteUrl/SiteAssets/__extendedHeaderBackgroundImage__DEFAULT_CHROME_BG_IMAGE_NAME.png" `
    -SiteThumbnailUrl "/sites/$siteUrl/SiteAssets/__sitelogo__credimus-icon@2x.png" `
    -SiteLogoUrl "/sites/$siteUrl/SiteAssets/__rectSitelogo__credimus-full@2x.png"
Set-PnPWeb -Connection $newSiteConnection -HideTitleInHeader

Start with the Get-PnPSiteTemplate export path and the configuration handling for SiteHeader and SiteFooter. Reproduce the export using the issue's JSON handler settings, then verify that the generated Header and Footer elements retain the modern settings shown by the cmdlets; done means those settings are present in the exported template.