The CompilationStencil::input still has GC pointers in some cases which is problematic for adding a new API for stencil. This bug tries to untangle that.

Use the UniquePtr overloads everywhere to reduce code duplication.

Depends on D104885

Move the CompilationInput out of CompilationStencil and trace that instead.
For now, the CompilationStencil continues to have a reference to the input so
care must be taken. Note that the compile options were already a reference so
this footgun already existed. Later patches will simplify this.

Depends on D104886

Move these methods to the stencil since we will more ScriptSource in
subsequent patches.

Depends on D104887

The ScriptSource no longer requires GC-tracing so we want it out of the
CompilationInput and on the CompilationStencil.

Depends on D104888

The Parser / BCE should use CompilationState instead of trying to access the
information through the CompilationStencil.

Depends on D104889

This requires feeding in the CompileOptions for both encoding (which checks
options), and decoding (which needs flags like 'mutedErrors' for the
ScriptSource).

Depends on D104890

This requires explicitly passing the 'input' data into the instantiation code
in order to access atom-cache and enclosing-scope-chain.

The CompilationStencil is now entirely decoupled from the GC and no tracing
or references to traced objects are required anymore.

Depends on D104938

https://hg.mozilla.org/mozilla-central/rev/7a16727c6518
https://hg.mozilla.org/mozilla-central/rev/de199d2deec2
https://hg.mozilla.org/mozilla-central/rev/d83581a3c1a2
https://hg.mozilla.org/mozilla-central/rev/26455ae13f52
https://hg.mozilla.org/mozilla-central/rev/898f133e93a3
https://hg.mozilla.org/mozilla-central/rev/ae1d9fd6425e
https://hg.mozilla.org/mozilla-central/rev/78014b3ee746