fix(typescript): allow tslib peerDependency to be optional for npm and pnpm

[runspired]

Rollup Plugin Name: @rollup/plugin-typescript

This PR contains:

• bugfix
• feature
• refactor
• documentation
• other

Are tests included?

• yes (bugfixes and features will not be merged without tests)
• no

Testing this would be akin to testing npm.

Breaking Changes?

• yes (breaking changes will not be merged unless absolutely necessary)
• no

If yes, then include "BREAKING CHANGES:" in the first commit message body, followed by a description of what is breaking.

List any relevant issue numbers:

• Remove tslib from peerDependencies of typescript plugin #265

Description

tslib is an optional dependency and in a large set of projects goes completely unused (notably anything compiling with babel or which does not require use of the helpers).

Historically, yarn and npm would warn for peerDependencies but not error, but as better package managers have fixed this mistake (most notably pnpm) and worked their way into being industry defaults this behavior has shifted from minor-nuisance to build-breaking.

This PR uses the spec peerDependencyMeta respected by both npm and pnpm to declare the tslib peerDependency as entirely optional.

[shellscape]

our issue and pull request templates are not optional. please replace the template and fill it in and it's entirety if you would like to move forward.

[runspired]

@shellscape apparently they are optional as opening one in this manner didn't give me one :P (This manner meaning editing the file via the github interface and selecting the open-pr option)

[shellscape]