RFR: 8269806: Emoji rendering on Linux [v4]

[Nikita Gubarkov]

> It was implemented in JetBrains Runtime a year ago and was ported & refactored for this PR
> It includes:
> - Bitmap glyph loading via Freetype
> - Manual scaling & transformation of bitmap glyphs with nearest-neighbor or bilinear-mipmap style algorithms depending on the text antialiasing hint
> - Storing BGRA glyphs in glyph cache & rendering them as plain images, as currently used XRender text drawing functions doesn't support colored glyphs
> - Small fixes in related code like null-checks which could cause NPE & comment typos

Nikita Gubarkov has updated the pull request incrementally with two additional commits since the last revision:

 - 8269806: Fix rendering of colored glyphs on big font sizes
   
   When using OutlineTextRenderer, fallback to GlyphListPipe for glyphs which doesn't have outlines.
 - 8269806: Fix glyph advance rounding with FM=OFF

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Changes:
  - all: https://git.openjdk.org/jdk/pull/4798/files
  - new: https://git.openjdk.org/jdk/pull/4798/files/9dbed75f..e8b1adab

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=4798&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=4798&range=02-03

  Stats: 288 lines in 9 files changed: 154 ins; 100 del; 34 mod
  Patch: https://git.openjdk.org/jdk/pull/4798.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/4798/head:pull/4798

PR: https://git.openjdk.org/jdk/pull/4798