Shows text in the current font at the current text position (Tj, or TJ when it is kerned).
public void ShowText(ReadOnlySpan<char> text, bool kerning)
The text; every character shall have a code in the font (CanEncode(ReadOnlySpan<Char>)).
Whether to apply the font's kerning between neighbouring glyphs, written as TJ adjustments (MeasureWidth(ReadOnlySpan<Char>, Double, Boolean) measures the same advance).
ISO 32000-2 §9.4.3, Table 107 (Tj, TJ), and §9.4.4: each glyph advances the text matrix by its width at the font
size plus the character spacing (and the word spacing for code 32), times the horizontal scaling. A kerning amount k
(thousandths of the font size) is written as the TJ number −k.