Add fonts (& infrastructure) to Alpine images

[TobiX]

Issue #, if available: #112 & #108

Description of changes:

Instead of creating a new "headless" variant of the Alpine images, this just adds font-droid to all the Alpine images. This pulls in fontconfig & freetype, which allows Java/AWT to render fonts (see #108 for details). This only adds about 6MB to each image, which I find reasonable.

I selected Droid, since it is a bit smaller then other fonts, under a simple license (Apache 2.0) and has a reasonable selection of alternatives (Serif, Sans-Serif, Mono)

Size comparison

For reference, here is a list of images with different fonts included:

localhost/corretto-8-jre-dejavu      latest        8a58b4581222  17 minutes ago  133 MB
localhost/corretto-8-jre-freefont    latest        85d045e180db  17 minutes ago  129 MB
localhost/corretto-8-jre-noto        latest        d09ff1c4dc7b  17 minutes ago  135 MB
localhost/corretto-8-jre-droid       latest        bd1d14675e33  17 minutes ago  123 MB
localhost/corretto-8-jre-opensans    latest        f0a3f149c4e7  17 minutes ago  125 MB
localhost/corretto-8-jre-liberation  latest        f8aa030f28f4  17 minutes ago  126 MB
docker.io/library/amazoncorretto     8-alpine-jre  e79af4bd4f9e  13 days ago     116 MB

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