fix(compute/build): ignore all files except manifest and wasm binary

[Integralist]

We can see that the new 'default' build of a package only contains the main.wasm and fastly.toml manifest...

$ list_contents pkg/testing-fastly-cli.tar.gz

drwx------  0 integralist staff       0 21 Feb 14:43 testing-fastly-cli/
drwx------  0 integralist staff       0 21 Feb 14:43 testing-fastly-cli/bin/
-rw-r--r--  0 integralist staff 12195738 21 Feb 14:43 testing-fastly-cli/bin/main.wasm
-rw-r--r--  0 integralist staff      320 21 Feb 14:43 testing-fastly-cli/fastly.toml

But if we specify --include-source...

$ fastly compute build --include-source
✓ Initializing...
✓ Verifying package manifest...
✓ Running [scripts.build]...
✓ Creating package archive...

SUCCESS: Built package (pkg/testing-fastly-cli.tar.gz)

...then we'll find more contents inside the package...

$ list_contents pkg/testing-fastly-cli.tar.gz

drwx------  0 integralist staff       0 21 Feb 14:47 testing-fastly-cli/
drwx------  0 integralist staff       0 21 Feb 14:47 testing-fastly-cli/bin/
-rw-r--r--  0 integralist staff     850 21 Feb 14:47 testing-fastly-cli/bin/index.js
-rw-r--r--  0 integralist staff 12195760 21 Feb 14:47 testing-fastly-cli/bin/main.wasm
-rw-r--r--  0 integralist staff      320 21 Feb 14:47 testing-fastly-cli/fastly.toml
drwx------  0 integralist staff        0 21 Feb 14:47 testing-fastly-cli/src/
-rw-r--r--  0 integralist staff     2821 21 Feb 14:47 testing-fastly-cli/src/index.js
-rw-r--r--  0 integralist staff      666 21 Feb 14:47 testing-fastly-cli/src/[email protected]

[JakeChampion]

This is the default location that @fastly/js-compute will write to but it can be configured to write to any location. Should we provide a configuration option in the fastly compute build command to specify the wasm location?

[Integralist]

We currently document the expectation that the main.wasm needs to exist inside the bin directory:

So although it might be possible to change this, for this PR I think we're OK 👍🏻