Inconsistent build-tag naming for disabling batteries

[ttn-ttn]

Batteries are disabled with a no_<feature> build tag, paired with a builtins_<feature>_not.go stub carrying the same tag. Several places deviate from this:

1. builtins_sxml_not.go is guarded by not_sxml, while builtins_sxml.go uses !no_sxml. The two tags don't match, so -tags no_sxml excludes both files and the build breaks:

$ go build -tags no_sxml github.com/refaktor/rye
batteries/builtins_structures.go:67:16: undefined: load_saxml_Dict batteries/register.go:56:27: undefined: Builtins_sxml

2. builtins_term.go and builtins_termstr.go are guarded by b_no_term, while the other batteries use the no_<feature> form.

3. Build scripts pass disable tags that no source file reads, so they have no effect:

• no_termui in buildwasm and .goreleaser.yaml (the battery tag is no_tui)
• b_no_io in build_tinygo (the battery tag is no_io)

[refaktor]

I moved most of the files with built-ins that could be called "batteries" into batteries/ subfolder and base but IO related to baseio/ folder.

That was for general organization, but also so I could produce a package rye/embed that people can use to embed just the Rye with minimal dependencies (without all the batteries and also without IO) into specific Go project.

I need to still move some files around, perhaps even split them or group them differently. Then I will get to look at these flags and try to find a coherent system for flags.