meson: Use feature.require() and feature.allowed()

meson: Use feature.require() and feature.allowed()

To reduce the size and complexity of checks. require() allows combining
auto and enabled checks(), so that something like
```meson
x = get_option('feature')
y = false
if x.enabled()
  if not condition
    error(...)
  endif
  y = condition
endif
```
can be rewritten as:
```meson
y = get_option('feature').require(condition, error_message : ...).allowed()
```
require checks the condition, then if the feature is required it emits
an error with the given message otherwise it returns a disabled feature.
allowed then returns whether the feature is not disabled, and returns
that (ie, .allowed() == not .disabled()). This is especially helpful for
longer more complex conditions

Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>