bevy_reflect incorrectly looks for bevy in dev-deps

[Moxinilian]

When trying to determine how it should mention itself in derive macros, the crate finder incorrectly assumes it can use bevy::reflect if bevy is available as a dev dependency. This PR fixes this behavior by ignoring dev-dependencies.

[Moxinilian]

After giving it some thought I realized this means bevy_reflect will no longer work in situations in which examples need bevy_reflect only as a dev dependency. I need to change this.
Implemented in following commit.

[cart]

Hmm isn't this effectively a no-op change?

How is accepting both dev and normal deps different from first accepting normal, then falling back to dev?

[Moxinilian]

Consider the following:

[dependencies]
bevy_reflect = "*"

[dev-dependencies]
bevy = "*"

Originally, the first case would incorrectly use bevy::reflect in the main crate code (as bevy is found, which has priority), whereas here it will correctly pick up bevy_reflect in all cases (as it is always available). This was incorrect because dev-dependencies are not available to main crate code.

Now consider the following:

[dependencies]
# nothing

[dev-dependencies]
bevy = "*"

Without the dev-deps fallback, bevy would not be located if the examples use bevy::reflect.

[cart]

Ah right. I wasn't considering the case where you have the full bevy crate and a subcrate.