Fix some server rebuild issues for non-HTML custom output formats

The failing test case here is

* A custom search output format defined on the home page, marked as `noAlternative` and not `permalinkable`
* In fast render mode, when making a change to a data source for that search output format, the JSON file was not refreshed.

There are variants of the above, but the gist of it is:

* The change set was correctly determined, but since the search JSON file was not in the recently visited browser stack, we skipped rendering it.

Running with `hugo server --disableFastRender` would be a workaround for the above.

This commit fixes this by:

* Adding a check for the HTTP request header `Sec-Fetch-Mode = navigation` to the condition for if we should track server request as a user navigation (and not e.g. a HTTP request for a linked CSS stylesheet).
* Making sure that we compare against the real relative URL for non-permalinkable output formats.

Fixes #13014

hugolib/site_render.go

@@ -20,6 +20,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/bep/logg"
 	"github.com/gohugoio/hugo/common/herrors"
 	"github.com/gohugoio/hugo/hugolib/doctree"
 
@@ -33,6 +34,8 @@ import (
 type siteRenderContext struct {
 	cfg *BuildCfg
 
+	infol logg.LevelLogger
+
 	// languageIdx is the zero based index of the site.
 	languageIdx int
 
@@ -86,7 +89,7 @@ func (s *Site) renderPages(ctx *siteRenderContext) error {
 		Tree: s.pageMap.treePages,
 		Handle: func(key string, n contentNodeI, match doctree.DimensionFlag) (bool, error) {
 			if p, ok := n.(*pageState); ok {
-				if cfg.shouldRender(p) {
+				if cfg.shouldRender(ctx.infol, p) {
 					select {
 					case <-s.h.Done():
 						return true, nil