Replace `outs` with `inits` in linalg textual assembly

[mehdi_amini]

Summary

The "outs" is confusing for the tensor domain as these are immutable
object. These arguments are used for:

• the iteration domain / shape of the results.
• the initial value used when reduction are involved.

[pifon2a]

Thanks!

[mehdi_amini]

I'll wait to hear at least from @mravishankar @nicolasvasilache here.

[nicolasvasilache]

I don't have strong opinions here, all names are confusing ..

init makes one think that the tensor needs to be initialized to a meaningful value, this is not the case if the associated bbArg is not used.
out confuses people for other reasons.

if anything, I'd go for dest personally with a doc that the dest may or may not be read.

[mehdi_amini]

In D146036#4192786, @nicolasvasilache wrote:

if anything, I'd go for dest personally with a doc that the dest may or may not be read.

dest looks to me like "writing to a tensor" again. The "destination" of the tensor-based op is the LHS of the = and the "yielded" values in the body.