feat: esm format

[petyosi]

Fixes #501. I tried to touch as few things as possible, as I am unaware of the implications.

What to look for:

• I changed the way we deal with version reporting. Look hard at it and see if it breaks something.
• Tried to bundle everything into a single file, did not work for some reason (./utils were not bundled). Kept the original format.

[github-actions]

Size Change: 0 B

Total Size: 98.7 kB

ℹ️ View Unchanged

Filename	Size
dist/js_min/getstream.js	31 kB
dist/js/getstream.js	67.8 kB

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