Hamza/hackweek0725 lazy copying support

[HamzaShili65]

Add support for lazy copying to the file resource + acceptance test.
Test results:

    resource_file_test.go:584: Skipping Nomad provider transport apply: ENOS_TRANSPORT_HOST env var not set. Please set it to test this scenario.
--- PASS: TestAccResourceFileLazyCopyMissingSourceFile (3.19s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/resource_transport_plan_[ssh]_lazy_copy_missing_source (0.33s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/resource_transport_apply_[ssh]_lazy_copy_missing_source (0.25s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/provider_transport_plan_[ssh]_lazy_copy_missing_source (0.32s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/provider_transport_apply_[ssh]_lazy_copy_missing_source (0.25s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/resource_transport_plan_[k8s]_lazy_copy_missing_source (0.33s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/resource_transport_apply_[k8s]_lazy_copy_missing_source (0.24s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/provider_transport_plan_[k8s]_lazy_copy_missing_source (0.33s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/provider_transport_apply_[k8s]_lazy_copy_missing_source (0.24s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/resource_transport_plan_[nomad]_lazy_copy_missing_source (0.32s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/resource_transport_apply_[nomad]_lazy_copy_missing_source (0.24s)
    --- PASS: TestAccResourceFileLazyCopyMissingSourceFile/provider_transport_plan_[nomad]_lazy_copy_missing_source (0.33s)
    --- SKIP: TestAccResourceFileLazyCopyMissingSourceFile/provider_transport_apply_[nomad]_lazy_copy_missing_source (0.00s)

[ryancragun]

After we fix up the test cases we'll also want to increment the VERSION file by a patch. We might also want to revisit the schema docs for enos_file to mention lazy copying being supported.

There is also a make target that we run tfplugindocs or somesuch to generate the new docs.

[ryancragun]

We'll want to ensure that we check that a diagnostic is created during plan for the missing file.

We'll also want to test the inverse case where the file exists and doesn't render a diag.

[ryancragun]

It would also be nice to throw in a copy for a lazy file in one of the enos scenarios that we run during our CI.