export parsed composite specs

[grokspawn]

Description of the change:
export parsed yaml/json specs so that other tooling can leverage it

Motivation for the change:
tap-fitter tooling will be able to generate some pipeline-specific pieces from the composite template, but the current implementation parses and executes the specs in an uninterrupted flow

example:

c := composite.NewTemplate(
         composite.WithCatalogFile(tempCatalog),
         composite.WithContributionFile(compositeReader)
)
specs, err := c.Parse()

Reviewer Checklist

• Implementation matches the proposed design, or proposal is updated to match implementation
• Sufficient unit test coverage
• Sufficient end-to-end test coverage
• Docs updated or added to /docs
• Commit messages sensible and descriptive

[grokspawn]

/hold for consolidating types

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@56771f7). Click here to learn what that means.
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1139   +/-   ##
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  Coverage          ?   53.82%           
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  Files             ?      108           
  Lines             ?    10199           
  Branches          ?        0           
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  Hits              ?     5490           
  Misses            ?     3741           
  Partials          ?      968           

Files Changed	Coverage Δ
alpha/template/composite/composite.go	79.50% <100.00%> (ø)

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[oceanc80]

/lgtm

[everettraven]

Looks good to me.

I do have a teeny nit (totally non-blocking) - I personally prefer to have methods co-located with the type they are associated with because it makes it easier for me to dig into the code due to less jumping between different files.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: everettraven, grokspawn

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[grokspawn]

/unhold

[grokspawn]

Looks good to me.

I do have a teeny nit (totally non-blocking) - I personally prefer to have methods co-located with the type they are associated with because it makes it easier for me to dig into the code due to less jumping between different files.

I'm of two minds on this. But we already had a types.go file for composite templates, and I thought it was confusing to have some types there, but not others. So when considering whether to obsolete the module and move all the types here, or add a couple more types to that one .... I landed on the 'consolidation' move.

If we find that it causes issue later, I'm totally OK with a future PR to move them out of that file so we can have everything in one place.