add support for passing arguments to services

[q66]

The argument is a part of the full service name always. Therefore, each argument instantiation is a separate instance of the service, with separate loading.

The following cases are supported:

1. passing the argument to any dinitctl command that takes an a service name
2. dependencies with an argument
3. using the argument in any context that does variable substitution
4. using the argument in dependency arguments (performing a restricted version of variable substitution)

documentation is updated, load+integration tests are updated/added

while at it, i found that depends-ms.d was being parsed wrong (it was never reading the dir) so i fixed that too

[q66]

i'm a bit confused by the aarch64 failure after i force pushed?

[q66]

actually that was probably just a readiness race for the dependency chain, i made all the dependencies scripted (that should address that)

[davmac314]

I had a quick look and it seems ok, I'll review properly on the weekend