Use weight `constants::` in the weight template

[ggwpez]

The weight template currently outputs something like (x as Weight) which is semantically not very clear.
Changing this to (x * constants::WEIGHT_PER_NANOS) with the correct units would be much better.

One possible approach:

• Write a function that correctly formats the weight, eg. 38_000_000 becomes 38_000 * WEIGHT_PER_NANOS
• PS: Better call this function directly from the template

WEIGHT_PER_NANOS is probably the only one that we can use, as it would otherwise use float point multiplication.

[hzy1919]

@ggwpez hi , I am attempting this issue.

[ggwpez]

Ok great @hzy1919 !

I added some possible was of implementation. Should be rather easy.

[hzy1919]

@ggwpez Thanks for your help! I commit a PR #11233 .

[ggwpez]

Will be drastically changed after #10918 anyway. We can think of a better format in there.