Add option to ingore services

[Calandracas606]

Pretty self explanatory. If I dont want to enable some services which would be enabled by default (elogind, polkit), I can disable them with -D "elogind polkit"

I'm not sure if I should be committing the generated content from make README.md

[paper42]

as far as I remember, all services have to be explicitly enabled with an argument to mklive. Just don't list the services if you don't want them to be enabled.

[Calandracas606]

when using build-x86-images.sh some services are passed implicitly

[paper42]

then just edit build-x86-images.sh, I don't see a reason to have a mklive.sh argument that removes services that were added by another argument, just remove it from that argument

[Calandracas606]

For more context, I'm ignoring some packages when building by using the -g "eudev dbus elogind" which would otherwise be enabled by default

The image fails to build because mklive.sh tries to enable the services which are provided by packages which have been ignored.

This use case is very niche, and if this doesn't seem useful then go ahead and close the PR

[classabbyamp]

as of #384 i've started moving these stringy arrays to bash arrays, would be nice to do here too.

imo this is the most concise way of checking for array membership: https://github.com/void-linux/void-packages/pull/42656/files#diff-2aed335c529e5e6ba673dd15b329eba3605f22c2762850121093db28c4fa2f93R325-R328