feat: add core module with app config support

[aaronc]

Description

Ref: #11899

This initializes app wiring officially in the SDK by adding the cosmossdk.io/core go module with two packages:

• appmodule for registering module implementations
• appconfig for loading declarative app configs

---

Author Checklist

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I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
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• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
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Reviewers Checklist

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I have...

• confirmed the correct type prefix in the PR title
• confirmed ! in the type prefix if API or client breaking change
• confirmed all author checklist items have been addressed
• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)

[alexanderbez]

Looks solid!

[alexanderbez]

we'll update this once we update the api module vanity URL and tag it.

[codecov]

Codecov Report

Merging #11914 (a56f286) into main (40b5953) will decrease coverage by 0.25%.
The diff coverage is 79.68%.

@@            Coverage Diff             @@
##             main   #11914      +/-   ##
==========================================
- Coverage   66.30%   66.04%   -0.26%     
==========================================
  Files         689      676      -13     
  Lines       72303    71346     -957     
==========================================
- Hits        47943    47124     -819     
+ Misses      21635    21538      -97     
+ Partials     2725     2684      -41     

Impacted Files	Coverage Δ
core/appconfig/config.go	79.68% <79.68%> (ø)
container/struct_args.go
container/one_per_module.go
container/build.go
container/container.go
container/option.go
container/simple.go
container/module_dep.go
container/group.go
container/debug.go
... and 5 more

[JeancarloBarrios]

Great!!