Add source details to error message

[austinvalle]

A hackish fix to close #133, another alternative could be submitting a PR upstream to hc-install to add Stringer implementations for each src.Source implementation.

The upstream hc-install src.Source interface does not provide a String() function or equivalent to retrieve relevant information about the sources.

This PR takes some of the source detail from the logging message and adds all source detail information to the end of an error message. It's provides maybe too much information now instead of none 😆.

# Example w/ incorrect version env variable
cannot run Terraform provider tests: error ensuring Terraform CLI binary: failed to obtain product version from "https://releases.hashicorp.com/terraform/1.5.2/index.json": 404 Not Found  -  attempted source(s): [Terraform CLI source of releases.hashicorp.com exact version "1.5.2" for installation in: /var/folders/t8/1tjpvj_d24x8yl0st5qswzf80000gp/T/plugintest-terraform4283162721]

# Example w/ network error
cannot run Terraform provider tests: error ensuring Terraform CLI binary: Get "https://releases.hashicorp.com/terraform/1.5.0/index.json": dial tcp: lookup releases.hashicorp.com: no such host -  attempted source(s): [Terraform CLI source of releases.hashicorp.com exact version "1.5.0" for installation in: /var/folders/t8/1tjpvj_d24x8yl0st5qswzf80000gp/T/plugintest-terraform856199534]