Generate Bindata iff TAGS="bindata" and not up-to-date (#10004)

* Only generate bindata if necessary

* Only generate bindata if they are not up-to-date

* generate a hash of the fileinfo and use that to keep up-to-date

* Newer test is redundant

* handle missing bindata and clean

* Only update hash after successful write

* switch to sha1 hash

* Apply suggestions from code review

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

Co-authored-by: guillep2k <18600385+guillep2k@users.noreply.github.com>

.gitignore

@@ -34,8 +34,11 @@ _testmain.go
 coverage.all
 
 /modules/options/bindata.go
+/modules/options/bindata.go.hash
 /modules/public/bindata.go
+/modules/public/bindata.go.hash
 /modules/templates/bindata.go
+/modules/templates/bindata.go.hash
 
 *.db
 *.log