Support deferred blocks in partial compilation

[crisbeto]

Includes some changes that are necessary to support @defer blocks in partial compilation mode.

refactor(compiler): ensure defer blocks maintain the template order in the binder

Switches to tracking the deferred blocks in a flat array in the binder to ensure that their template order is maintained. This will be relevant in the next commits where we'll match deferred blocks by their index.

Note that the current map we have technically guarantees the insertion order in the spec, but the array is a bit more explicit.

refactor(compiler): widen type of resolver function

Updates the type of the resolver function to be any Expression since JIT may receive a function reference rather than a ArrowFunctionExpr.

refactor(compiler-cli): add method for extracting function parameters

Updates the linker's AST host to add the ability to extract a function's parameters. This will be required for the next commits.

refactor(core): introduce API for declaring asynchronous partial metadata

Adds the ɵɵngDeclareClassMetadataAsync function that will be produced during partial compilation for component classes that have deferred dependencies. At runtime the dependencies will be resolved before setting the metadata.

feat(compiler-cli): add partial compilation support for deferred blocks

Builds on top of the previous changes to add support for deferred blocks during partial compilation. To do this, the following changes had to be made:

• The metadata passed into ɵɵngDeclareComponent has an additional field called deferBlockDependencies which has an array of the dependency loading functions for each defer block in the template. During linking, the dependency functions are loaded by matching their template index to the index in the deferBlockDependencies array.
• There's a new ɵɵngDeclareClassMetadataAsync function that is created for components that have deferred dependencies. It gets transpiled to setClassMetadataAsync and works in the same way by capturing a dependency loading function and setting the metadata after the dependencies are resolved. It also has some extra fields for capturing the version which are standard in linker-generated code.
• Deferred import statements are now stripped in partial compilation mode, similar to full compilation.

[AndrewKushnir]

@crisbeto the change looks great 👍 Huge thanks for splitting the change into multiple commits, it made it much easier to review.

[AndrewKushnir]

@alxhub could you please take a look at this change when you get a chance? Would love to get your feedback on the shape of partially compiled components. Thank you.

[JoostK]

LGTM with one comment

[dylhunn]

This PR was merged into the repository by commit 5bd188a.

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