feat(bundle-source): Add tag command-line flag

[kriskowal]

Refs: #400

Description

We’ve discovered that, to create an Endo script bundle that captures our ModuleSource constructor shim, it will need to entrain Babel. With the default build conditions, Babel entrains a debug package, which entrains node:tty. So, it is necessary to add the "browser" condition, which instead entrains a package with a JSON module (#2352). This change threads arbitrary conditions (build tags) through bundle-source to conveniently generate Endo script bundles with different tags like browser or xs.

Security Considerations

None.

Scaling Considerations

None.

Documentation Considerations

The new flags are advertised in the command’s usage display.

Testing Considerations

• test scaffold and manual testing instructions

Compatibility Considerations

None.

Upgrade Considerations

None.

[erights]

With the default build conditions, Babel entrains a debug package, which entrains node:tty.

Are there better behaved non-default build conditions?

[erights]

nevermind. I get it now.

[erights]

Simple! LGTM!

[dckc]

... it will need to entrain Babel.

it = ?

I'm not sure I'm following.

[kriskowal]

an Endo script bundle that captures our ModuleSource constructor shim,

An Endo script bundle that captures our ModuleSource constructor shim (née @endo/static-module-record) such that a test262 “prelude” (shim script) can arrange for the same environment as XS, so we can write test262 tests that expect the same Hardened JavaScript environment.