style: name each predicate after the grammar it encodes, not the file

`golangci_takes_value` is not golangci's grammar -- it is the global one, the
flags valid before a subcommand, with `golangci_run_takes_value` alongside it
for `run`'s. The module prefix said the wrong thing and repeated the file name,
so they become `global_takes_value` and `run_takes_value`, matching how git.rs
names its per-subcommand grammars. `is_golangci_subcommand` loses the same
redundant prefix and now reads like its neighbour `find_subcommand_index`.

`bare_double_dash_flag` sat unprefixed between five `dotnet_*` token lookups
doing the same job; it joins them as `dotnet_has_bare_double_dash_flag`,
matching `dotnet_has_bare_loose_flag` directly above it.

Naming is per family, not per file: dotnet's `has_*_arg` feature detectors and
search's `is_*_token` flag classifiers are each internally consistent and stay
as they are.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>