Add a before-body partial to allow targeting preamble content

Fixes #5058

news/changelog-1.4.md

@@ -84,6 +84,7 @@
 
 - ([#4370](https://github.com/quarto-dev/quarto-cli/issues/4370)): Hoist code cells deep in the AST out of layout cells to avoid `\raisebox` issues with the `Shaded` environment.
 - ([#5078](https://github.com/quarto-dev/quarto-cli/issues/5078)): Ensure format-resources are copied before PDF rendering when `latex-auto-mk` is `false`
+- ([#5058](https://github.com/quarto-dev/quarto-cli/issues/5058)): Add a `before-title.tex` partial to the PDF format. This partial will appear in the document premable just before the title block, allowing further customization of the document preamble. By default, this partial is empty.
 - ([#5969](https://github.com/quarto-dev/quarto-cli/issues/5969)): Correctly detect a required rerun for biblatex when using backref link options.
 - ([#5690](https://github.com/quarto-dev/quarto-cli/issues/5690)): Improve validation of `pdf-engine`
 - ([#6077](https://github.com/quarto-dev/quarto-cli/issues/6077)): Make sure proof environments are tight around contents.

src/format/pdf/format-pdf.ts

@@ -241,6 +241,7 @@ function createPdfFormat(
           "pandoc",
           "tables",
           "tightlist",
+          "before-title",
           "title",
           "toc",
         ];

src/resources/formats/pdf/pandoc/template.tex

@@ -367,6 +367,7 @@
 $endif$
   pdfcreator={LaTeX via pandoc}}
 
+$before-title.tex()$
 $title.tex()$
 
 \begin{document}