Expose std in the inline jk execution

[dlespiau]

Extracted from #188.

We currently import specific symbols from std in the inline template (log, write, read) we could, instead, do:

import * as std from '@jkcfg/std/std';

so we don't miss symbols (such as Format) and are future (eg. I'd like to add a logerr that outputs to stderr).

[squaremo]

Just to set out some trade-offs:

• Given that the standard library is built into the runtime, its contents will be static for a particular release. So the sense in the which this is future-proof is that it doesn't need to be adjusted in the jk source code when a named export is added to std -- and not (as might initially seem the case) that the runtime will automatically pick up new capabilities when things are added to the standard library.

• It makes inline scripts a little more wordy, because they'll have to include std. when referring to things from std (this can be regarded as a positive too)

• scripts that try to use things not in std can fail in less obvious ways. For example, if I try to use std.format instead of std.Format as a value, the script will run and I'll (probably) get an unexpected output; whereas, if I try to use format instead of Format, the script will fail to compile.