[Build] Remove tslib reference in es6 packages (First step towards esm)

[RaananW]

Fixes #12784

This PR removes the tslib dependency (while still providing it locally in its es6 version). This will allow using the es6 packages in the browser directly and will minimally help tree shaking, as not all of tslib is even needed (ATM only decorators).

Another change - the output for the esm packages is no longer es5! it is now es2021.

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Reviewer - this PR has made changes to one or more package.json files.

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Please make sure to label your PR with "bug", "new feature" or "breaking change" label(s).
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Reviewer - this PR has made changes to one or more package.json files.

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Reviewer - this PR has made changes to one or more package.json files.

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Snapshot stored with reference name:
refs/pull/12897/merge

Test environment:
https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12897/merge/index.html

To test a playground add it to the URL, for example:

https://babylonsnapshots.z22.web.core.windows.net/refs/pull/12897/merge/index.html#WGZLGJ#4600

Links to test babylon tools with this snapshot:

https://playground.babylonjs.com/?snapshot=refs/pull/12897/merge
https://sandbox.babylonjs.com/?snapshot=refs/pull/12897/merge
https://gui.babylonjs.com/?snapshot=refs/pull/12897/merge
https://nme.babylonjs.com/?snapshot=refs/pull/12897/merge

To test the snapshot in the playground with a playground ID add it after the snapshot query string:

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[RaananW]

@sebavan - no package was released yet that supports this. this is just a TODO list for both of us to quickly discuss side effects of this change