fix: module library export generation for reexport

[alexander-akait]

What kind of change does this PR introduce?

bugfix - #19386 (comment)

Did you add tests for your changes?

Yes

Does this PR introduce a breaking change?

No

What needs to be documented once your changes are merged?

No

/cc @JSerFeng

Looks like we still need generate var/const extra variable for reexport exports, otherwise we can faced with the same top level name in scope

[github-actions]

Benchmarks:

• "devtool-source-map": HEAD (c0a8664) 651 ms ± 47 ms [640 ms; 662 ms] (51 runs)
• "devtool-source-map": BASE (519187b) 637 ms ± 38 ms [628 ms; 646 ms] (52 runs)
• "devtool-source-map" change: HEAD (651 ms ± 47 ms [640 ms; 662 ms]) is -2% the same as BASE (BASE) (637 ms ± 38 ms [628 ms; 646 ms])

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• "many-chunks": HEAD (c0a8664) 1088 ms ± 35 ms [1077 ms; 1098 ms] (32 runs)
• "many-chunks": BASE (519187b) 1074 ms ± 29 ms [1065 ms; 1082 ms] (32 runs)
• "many-chunks" change: HEAD (1088 ms ± 35 ms [1077 ms; 1098 ms]) is -1% the same as BASE (BASE) (1074 ms ± 29 ms [1065 ms; 1082 ms])

---

• "many-modules": HEAD (c0a8664) 584 ms ± 24 ms [579 ms; 590 ms] (55 runs)
• "many-modules": BASE (519187b) 588 ms ± 28 ms [581 ms; 594 ms] (55 runs)
• "many-modules" change: HEAD (584 ms ± 24 ms [579 ms; 590 ms]) is 1% the same as BASE (BASE) (588 ms ± 28 ms [581 ms; 594 ms])

---

• "popular-libraries": HEAD (c0a8664) 1470 ms ± 31 ms [1460 ms; 1481 ms] (25 runs)
• "popular-libraries": BASE (519187b) 1522 ms ± 47 ms [1505 ms; 1538 ms] (24 runs)
• "popular-libraries" change: HEAD (1470 ms ± 31 ms [1460 ms; 1481 ms]) is 4% faster than BASE (BASE) (1522 ms ± 47 ms [1505 ms; 1538 ms])

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[JSerFeng]

Thanks! LGTM, and we need to align this in Rspack as well

[alexander-akait]

@JSerFeng Improved it by checking top level