Binary Downloads - Allow user configurable location

[YOU54F]

Hey hey,

Up for discussion is the idea of binary downloads, and options for the user.

Previously Pact-PHP would attempt to download the binaries at test execution time, this has several drawbacks, and was removed in favour of providing the download of the appropriate binary at composer install time via a composer plugin. see #279 for detail

Some users may be restricted from the packages they install, fetching out to other sources to download required binaries.

We have seen the same issues for users in Pact-JS, whereby binaries were fetched in a post-install script, but some users have these disabled due to supply chain worries.

There are a couple of options

• Embed the binary packages directly in the source distributable

  • Either makes a large bundle supporting every arch
  • Separate packages, per arch, keeping the bundles as small as possible but fully self contained

• Download necessary binaries on install (as per current behaviour introduced in this pr)

  • For users that cannot or chose not to run pre or post install scripts, we should allow them to download the binaries directly (via existing means) and the language implementation allow the user to configure where their binaries reside.
  • Pact-Go uses the mechanism described above, whereby the user is expected to download the platform specific binary, and make it executable on the path.

  Thoughts and considerations welcome from users of the pact-php package, as I am not sure what is most important to you, when it comes to the additional sources required to make pact-php work (be it the ruby or rust backed core)

[YOU54F]

Also related is #227

[YOU54F]

Going to assume this isn't really wanted by the Pact PHP community.

Please feel free to comment back if this is important to you and it can be looked at again