Add ESM build to client

[acolytec3]

This replaces the current client build process with one that is ESM only.

Notable changes

• Adds a "type":"module" to package.json
• Adds a new ESM build step for npm run build
• Removes all require(... usage in client
• Revises imports of current CommonJS imports to use default imports and then destructuring as needed
• Removes fs-extra dependency since not needed (and was causing issues with the ESM build)
• Adds some typing in bin/cli.ts for the servers bit

TODOs:

• Completely remove the now non-functional CJS build

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.73%. Comparing base (61acbd3) to head (6f3324c).

❗ Current head 6f3324c differs from pull request most recent head 34fa97c. Consider uploading reports for the commit 34fa97c to get more accurate results

Additional details and impacted files

Flag	Coverage Δ
client	84.73% <100.00%> (?)
tx	?

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[jochem-brouwer]

Some initial comments

[gabrocheleau]

Why is this necessary? Can we just typecast instead?

[acolytec3]

I think this was an earlier left over. Looks like we don't need it at all. Will remove.

[gabrocheleau]

Left a couple of questions/comments. Looks great