Handle ChainRulesCore via Pkg extension

[oschulz]

Substantially reduces the load time of LinearMaps on Julia v1.9.

Before:

julia> @time import LinearMaps
  0.053604 seconds (73.57 k allocations: 4.871 MiB, 6.36% compilation time)

julia> @time_imports import LinearMaps, ChainRulesCore
      0.6 ms  Statistics
      0.2 ms  Compat
      0.2 ms  Compat → CompatLinearAlgebraExt
     24.7 ms  ChainRulesCore
     25.3 ms  LinearMaps

After:

julia> @time import LinearMaps
  0.037479 seconds (39.45 k allocations: 2.582 MiB, 12.74% compilation time)

julia> @time_imports import LinearMaps, ChainRulesCore
      0.5 ms  Statistics
     24.8 ms  LinearMaps
      0.2 ms  Compat
      0.1 ms  Compat → CompatLinearAlgebraExt
     30.9 ms  ChainRulesCore
      0.2 ms  LinearMaps → LinearMapsChainRulesCoreExt

[dkarrasch]

Thank you very much! Do you understand the complaint by Aqua.jl? Do we need to move the additions to Project.toml to a different place? The load time gain is great. Looks like almost all the load time is spent on ChainRulesCore?

[oschulz]

@dkarrasch The Aqua think I had hoped was handled now, but apparently not yet. It's just that Julia v1.6 formats Project.toml differently if there are weakdeps entries (which it doesn't know about) in it. So the Project.toml formatting tests has to be disabled on v1.6.

The invalidations failure seems unavoidable with Pkg extensions right now, see PainterQubits/Unitful.jl#652 .

[oschulz]

Aqua tests should pass now, hopefully.

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: +0.26 :tada:

Comparison is base (50ace9c) 99.41% compared to head (adfd37e) 99.67%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #206 +/- ## ========================================== + Coverage 99.41% 99.67% +0.26% ========================================== Files 19 19 Lines 1537 1538 +1 ========================================== + Hits 1528 1533 +5 + Misses 9 5 -4 ``` | [Impacted Files](https://app.codecov.io/gh/JuliaLinearAlgebra/LinearMaps.jl/pull/206?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaLinearAlgebra) | Coverage Δ | | |---|---|---| | [ext/LinearMapsChainRulesCoreExt.jl](https://app.codecov.io/gh/JuliaLinearAlgebra/LinearMaps.jl/pull/206?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaLinearAlgebra#diff-ZXh0L0xpbmVhck1hcHNDaGFpblJ1bGVzQ29yZUV4dC5qbA==) | `100.00% <ø> (ø)` | | | [src/LinearMaps.jl](https://app.codecov.io/gh/JuliaLinearAlgebra/LinearMaps.jl/pull/206?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaLinearAlgebra#diff-c3JjL0xpbmVhck1hcHMuamw=) | `100.00% <ø> (ø)` | | ... and [2 files with indirect coverage changes](https://app.codecov.io/gh/JuliaLinearAlgebra/LinearMaps.jl/pull/206/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaLinearAlgebra)

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[oschulz]

@dkarrasch This should be it now - from what I understand, the invalidations failure has to be ignored for now until with Pkg extensions, until that's handled upstream.

[dkarrasch]

Could you please bump the patch number and then I'll release shortly after merging. Thanks again!

[oschulz]

Version is bumped, thanks @dkarrasch !