Allow import of layout_test into 3rd party crates

[rollo-b2c2]

Description

This allows you to import layout_test into your crates as described in the docs. As you can't import things behind #[cfg(test)].

https://yew.rs/docs/more/testing

I think this was the intent of this PR

#2310

Should have no impact on the behavior of existing builds as you have to add yew/test to your build.

Fixes #3329

Checklist

• I have reviewed my own code
• I have added tests

[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	102.800	102.800	0	0.000%
boids	175.729	175.729	0	0.000%
communication_child_to_parent	95.273	95.273	0	0.000%
communication_grandchild_with_grandparent	109.013	109.013	0	0.000%
communication_grandparent_to_grandchild	105.675	105.675	0	0.000%
communication_parent_to_child	92.751	92.751	0	0.000%
contexts	113.392	113.392	0	0.000%
counter	89.155	89.155	0	0.000%
counter_functional	89.892	89.892	0	0.000%
dyn_create_destroy_apps	92.327	92.327	0	0.000%
file_upload	103.484	103.484	0	0.000%
function_memory_game	174.717	174.717	0	0.000%
function_router	352.578	352.578	0	0.000%
function_todomvc	163.478	163.478	0	0.000%
futures	227.812	227.812	0	0.000%
game_of_life	112.235	112.235	0	0.000%
immutable	188.923	188.923	0	0.000%
inner_html	85.940	85.940	0	0.000%
js_callback	113.412	113.412	0	0.000%
keyed_list	201.050	201.050	0	0.000%
mount_point	89.146	89.146	0	0.000%
nested_list	115.820	115.820	0	0.000%
node_refs	96.251	96.251	0	0.000%
password_strength	1721.057	1721.057	0	0.000%
portals	98.349	98.349	0	0.000%
router	318.554	318.554	0	0.000%
simple_ssr	144.036	144.036	0	0.000%
ssr_router	390.321	390.321	0	0.000%
suspense	119.004	119.004	0	0.000%
timer	91.755	91.755	0	0.000%
timer_functional	100.466	100.466	0	0.000%
todomvc	143.765	143.765	0	0.000%
two_apps	89.857	89.857	0	0.000%
web_worker_fib	138.845	138.845	0	0.000%
web_worker_prime	190.343	190.343	0	0.000%
webgl	88.461	88.461	0	0.000%

✅ None of the examples has changed their size significantly.

[github-actions]

Visit the preview URL for this PR (updated for commit 5634c02):

https://yew-rs-api--pr3463-patch-1-rmiwbw8k.web.app

_{(expires Fri, 20 Oct 2023 11:14:27 GMT)}

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[github-actions]

Benchmark - SSR

Yew Master

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	377.651	377.816	377.745	0.057
Hello World	10	641.761	650.948	645.133	2.427
Function Router	10	2131.403	2160.264	2149.425	7.917
Concurrent Task	10	1006.275	1008.135	1007.158	0.523
Many Providers	10	1535.088	1677.202	1562.241	43.074

Pull Request

Benchmark	Round	Min (ms)	Max (ms)	Mean (ms)	Standard Deviation
Baseline	10	377.702	378.085	377.813	0.111
Hello World	10	645.637	649.784	647.344	1.316
Function Router	10	2183.205	2241.010	2210.687	15.868
Concurrent Task	10	1006.115	1008.126	1007.473	0.673
Many Providers	10	1566.677	1713.970	1589.725	44.731

[ranile]

Looks good, thanks! It can be merged once CI is green

[aDogCalledSpot]

Can we have an update on this?

[ranile]

test may not be the best name for the feature but I also don't have a better name and it's always possible to rename it (still 0.x release)