Add Meson - for Kamaros

[hkaimio]

Kamaros projects uses Meson as a build system, this change adds Meson (and ninja which is required by it) to AsciiDoctor container.

[CLAassistant]

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[oddhack]

I just committed the equivalent change to main and proposed an MR to the Kamaros spec repo using the resulting image.

Closing this - I can't merge it in any event because there is something weird going on with GH Actions running out of resources, perhaps a billing issue, that I can't resolve right now.