fix(card): fix card and sub component render issues. Fixes #2062

[tmorehouse]

Description of PR:

Fixes #2026

Spreads children/slots when pushing elements onto build stack

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PR checklist:

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Enhancement to an existing feature
• ARIA accessibility
• Documentation update
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

The PR fulfills these requirements:

• It's submitted to the dev branch, not the master branch
• When resolving a specific issue, it's referenced in the PR's title (e.g. fixes #xxxx[,#xxxx], where "xxxx" is the issue number)

If new features/enhancement/fixes are added or changed:

• Includes documentation updates
• New/updated tests are included and passing (if required)
• Existing test suites are passing
• The changes have not impacted the functionality of other components or directives
• ARIA Accessibility has been taken into consideration (does it affect screen reader users or keyboard only users?)

If adding a new feature, or changing the functionality of an existing feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

PR titles should following the Conventional Commits naming convention

[codecov]

Codecov Report

Merging #2125 into dev will increase coverage by 0.06%.
The diff coverage is 95%.

@@            Coverage Diff             @@
##              dev    #2125      +/-   ##
==========================================
+ Coverage   64.81%   64.88%   +0.06%     
==========================================
  Files         156      156              
  Lines        2950     2950              
  Branches      812      810       -2     
==========================================
+ Hits         1912     1914       +2     
+ Misses        751      749       -2     
  Partials      287      287

Impacted Files	Coverage Δ
src/components/card/card-header.js	100% <ø> (ø)	⬆️
src/components/card/card-footer.js	100% <ø> (ø)	⬆️
src/components/card/card-img.js	63.63% <ø> (ø)	⬆️
src/components/card/card-body.js	100% <100%> (ø)	⬆️
src/components/card/card.js	95.45% <93.33%> (+8.49%)	⬆️

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