feat: deduplicate reexports and renderedExports to simplify output

[TrickyPi]

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

I think the existing test changes should cover it, but I'm not sure if the modifications of the 'system' test are correct, I need to learn about SystemJS.

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

List any relevant issue numbers:
resolves #4698

Description

[codecov]

Codecov Report

Merging #4759 (259b3f0) into master (b86e706) will decrease coverage by 0.01%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##           master    #4759      +/-   ##
==========================================
- Coverage   99.04%   99.03%   -0.02%     
==========================================
  Files         217      217              
  Lines        7734     7749      +15     
  Branches     2143     2147       +4     
==========================================
+ Hits         7660     7674      +14     
  Misses         24       24              
- Partials       50       51       +1     

Impacted Files	Coverage Δ
src/Chunk.ts	99.82% <94.73%> (-0.18%)	⬇️

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[TrickyPi]

I think the current changes are generating wrong System output, and the changes only have trivial effect on the amd and cjs output. Maybe we should move the changes to the es.ts or change system.ts?

[lukastaegert]

Yes, then do it just for es.

[rollup-bot]

This PR has been released as part of rollup@3.8.0. You can test it via npm install rollup.