feat: allow JS functions with .mjs extension

[eduardoboucas]

- Summary

Adds support for JavaScript functions using a .mjs extension. These functions will use the esbuild bundler.

Closes #588.

- Test plan

New test added.

- A picture of a cute animal (not mandatory but encouraged)

[github-actions]

⏱ Benchmark results

Comparing with 452f7ee

largeDepsZisi: 1m 4s

⬇️ 10.68% decrease vs. 452f7ee

^                 1m 11.7s                                                                                
│                   ┌──┐          1m 6.5s 1m 9.5s                 1m 8.3s                 1m 7.9s         
│ 1m 3.6s           |  |            ┌──┐    ┌──┐  1m 3.8s           ┌──┐  1m 3.4s 1m 4.1s   ┌──┐   1m 4s  
│ ──┌──┐──1m 2.1s───┼──┼────────────┼──┼────┼──┼────┌──┐────────────┼──┼────┌──┐────┌──┐────┼──┼────┌──┐──
│   |  |    ┌──┐    |  |            |  |    |  |    |  |            |  |    |  |    |  |    |  |    |▒▒|  
│   |  |    |  |    |  |   54.7s    |  |    |  |    |  |            |  |    |  |    |  |    |  |    |▒▒|  
│   |  |    |  |    |  |    ┌──┐    |  |    |  |    |  |   51.2s    |  |    |  |    |  |    |  |    |▒▒|  
│   |  |    |  |    |  |    |  |    |  |    |  |    |  |    ┌──┐    |  |    |  |    |  |    |  |    |▒▒|  
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│   |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |▒▒|  
│   |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |  |    |▒▒|  
└───┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴────┴──┴──>
    T-12    T-11    T-10    T-9     T-8     T-7     T-6     T-5     T-4     T-3     T-2     T-1      T    

Legend

• T-30 (452f7ee): 1m 10.9s
• T-29 (fcc82b7): 1m 14.8s
• T-28 (0862f9a): 1m 11.3s
• T-27 (8227298): 1m 9.5s
• T-26 (4bec0a7): 1m 2.7s
• T-25 (ccea887): 1m 12.5s
• T-24 (d9c0334): 1m 11.3s
• T-23 (58a459e): 59s
• T-22 (0b08454): 1m 3s
• T-21 (56f4d4a): 58.2s
• T-20 (7b77c56): 1m 14s
• T-19 (4a5a492): 1m 6.9s
• T-18 (38f4d47): 59.9s
• T-17 (f41a7a2): 1m 5.4s
• T-16 (65c4b94): 1m 15s
• T-15 (e6490d6): 59s
• T-14 (15787ef): 55.9s
• T-13 (1ce8157): 1m 2.9s
• T-12 (96c8335): 1m 3.6s
• T-11 (5d48d64): 1m 2.1s
• T-10 (bd7206e): 1m 11.7s
• T-9 (69fdb7b): 54.7s
• T-8 (57a644f): 1m 6.5s
• T-7 (a9a9e61): 1m 9.5s
• T-6 (8e299a2): 1m 3.8s
• T-5 (cebf521): 51.2s
• T-4 (b789589): 1m 8.3s
• T-3 (2e25a52): 1m 3.4s
• T-2 (fec9333): 1m 4.1s
• T-1 (bd61ad0): 1m 7.9s
• T (current commit): 1m 4s