The syntax of `http` `types` blocks is distinct, in that their child
directives are arbitrary MIME types - they therefore can't be analysed
when `strict` or `check_ctx` are enabled, and no meaningful analysis can
be performed when `check_args` is enabled because the arity of child
directives is unknown. Skip the checks performed when `strict` and
`check_ctx` are enabled, and hint to the analyser that all directives
inside a `types` block accept one or more arguments so that a meaningful
check can be performed when `check_args` is enabled.

Fixes nginxinc#101.

The `map` directive (from ngx_http_map_module and ngx_stream_map_module)
and `types` directive (from ngx_http_core_module) are distinct from
other directives, in that their child directives may be arbitrary
strings that aren't known to Nginx. This causes crossplane to report
unrecognised/misused directive errors when analysing them with `strict`
or `check_ctx` enabled; it also means that no meaningful analysis can be
be performed when `check_args` is enabled because the arity of child
directives is unknown.

Add support for `map`'s special directives (`default`, `hostnames`, and
`volatile`) to the analyser. Recognise that arbitrary directive names
inside a `map` or `types` block are valid and that they accept either
one argument (if used in `map`) or one or more arguments (if used in
`types`).

Fixes nginxinc#101 and nginxinc#103.

The `map` directive (from ngx_http_map_module and ngx_stream_map_module)
and `types` directive (from ngx_http_core_module) are distinct from
other directives, in that their child directives may be arbitrary
strings that aren't known to Nginx. This causes crossplane to report
unrecognised/misused directive errors when analysing them with `strict`
or `check_ctx` enabled; it also means that no meaningful analysis can be
performed when `check_args` is enabled because the arity of child
directives is unknown.

Add support for `map`'s special directives (`default`, `hostnames`, and
`volatile`) to the analyser. Recognise that arbitrary directive names
inside a `map` or `types` block are valid and that they accept either
one argument (if used in `map`) or one or more arguments (if used in
`types`).

Fixes nginxinc#101 and nginxinc#103.