PHP.wasm: Load correct php.wasm paths in the built Node.js packages (#…

…1877)

Gets `@php-wasm/node` and all the other CLI packages to load the .wasm
binaries from the correct path after #1867 introduced JSPI and #1873
made
 it pass all the tests in Node.js

 ## Technical details

In the repo, php.js files are stored in php_wasm/node/jspi or
php_wasm/node/asyncify.
 They start with a line like this:

 const dependencyFilename = __dirname + '/8_0_30/php_8_0.wasm';

After the build, the contents are concatenated into a single file, which
 breaks the dependencyFilename variable. This plugin corrects that by
replacing __dirname with the correct value such as 'jspi' or 'asyncify'.

The implementation is naive and assumes the substrings __dirname is only
used
as a variable, are not a part of any other name, and is not seen in any
string
 literals.

 ## Test plan

Build the production packages with `nx build php-wasm-node` and run the
PHP CLI package to confirm it doesn't crash. I couldn't get npm link to
work so I created a `dist/packages/php-wasm/node_modules/@php-wasm`
directory and linked all the built packages there with `ln -s`.