Allow duplicate keys if their values are the same

[knoepfel]

The utilities in de_std.libsonnet forbids duplicate keys. Although this prevents unintentional overwriting of configurations, it also prevents combining some configurations that use an identical configuration for a given key. This PR allows duplicate keys if the configuration values are the same.

[codecov[bot]]

Codecov Report

Merging #589 (11473c0) into master (1ea288e) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #589   +/-   ##
=======================================
  Coverage   84.20%   84.20%           
=======================================
  Files          46       46           
  Lines        2748     2748           
  Branches      492      492           
=======================================
  Hits         2314     2314           
  Misses        390      390           
  Partials       44       44           

Flag	Coverage Δ
python-3.10	84.13% <ø> (ø)
python-3.6	83.69% <ø> (ø)

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[jcpunk]

Can we break the pre-commit updates into a separate commit/PR?

[knoepfel]

@jcpunk, yep I'll make a separate PR.

[knoepfel]

See #592.

[knoepfel]

Will rebase this PR off of #592 once that is merged into master.

[mambelli]

I merged #592

[jcpunk]

pre-commit.ci run