Start printing on the paper of the document

[andiwand]

Follow-up to #710. The print dialog always started on the default paper of the printer, in portrait. An A4 document started on Letter, and a slide started on a portrait sheet.

Change

• PageSize (new, pure Kotlin): a page size in mils, made from a core Measure (in, cm, mm, pt, pc, px). It matches A3, A4, A5, Letter, Legal and Tabloid within 2%, which keeps A4 and Letter apart.
• CoreLoader: reads the page size of a text, presentation or drawing document. For text it uses TextRoot.pageLayout(), otherwise the first slide or page. The document is opened once, for this and for the editing check, so an editable format gets no extra decode. The value goes to LoadedDocument and is parcelled with it.
• PrintingManager: gives PrintManager.print a MediaSize for the paper and orientation. For a size without a standard paper, such as a 4:3 slide, it gives only UNKNOWN_LANDSCAPE or UNKNOWN_PORTRAIT. For a PDF printed from its file, PdfRenderer reads the size of the first page.

The print framework uses these attributes only as the start values. If the printer does not have the paper, the dialog falls back to the paper of the printer, and the user can still change it.

Verification

• PageSizeTest (5 tests) and the DocumentParcelTest round trip (6 tests, on the emulator) pass. spotlessCheck and lintProDebug pass.
• Pixel 6 Pro emulator, Pro debug build, print dialog with "Save as PDF":

File	Page	Dialog before	Dialog now
Casio_WVA-M650-7AJF.pdf	A4 portrait	Letter, portrait	ISO A4, portrait
speisekarte_helmarts.pdf	A4 landscape	Letter, portrait	ISO A4, landscape
style-various-1.pdf	Letter	Letter, portrait	Letter, portrait
style-various-1.odp	28 × 21 cm	Letter, portrait	Letter, landscape; 6 sheets for 6 slides
file-sample_100kB.odt	A4	Letter, portrait	ISO A4, portrait
sample.odg	A4	Letter, portrait	ISO A4, portrait; 3 sheets for 3 pages
file_example_XLSX_10.xlsx	none	Letter, portrait	Letter, portrait

I read the "before" column from #710's emulator run (Letter for the Casio PDF) and from the framework default; I did not rerun every row on the old build.