[SCVMM] Allow run_powershell_script method to accept file or string

[djberg96]

At the moment the run_powershell_script method in powershell.rb assumes that it's reading from a file. However, for provisioning requests the scripts are inlined as strings (heredocs), causing a Errno::ENAMETOOLONG error when it tries to read it as a file.

https://bugzilla.redhat.com/show_bug.cgi?id=1444201

I've updated the code to make a file check first, and assume that it's a string if it's not found as a file. I've also added some specs.

[djberg96]

@jteehan @bronaghs Please review.

[djberg96]

@miq-bot add_label fine/yes

[djberg96]

@miq-bot add_label euwe/no

[djberg96]

@miq-bot add_label darga/no

[miq-bot]

Checked commit https://github.com/djberg96/manageiq/commit/5a50ca672e701babe9c61f33754db1ef360777e8 with ruby 2.2.6, rubocop 0.47.1, and haml-lint 0.20.0
2 files checked, 5 offenses detected

spec/models/manageiq/providers/microsoft/infra_manager/powershell_spec.rb

• ❗ - Line 11, Col 7 - Style/SingleLineMethods - Avoid single-line method definitions.
• ❗ - Line 12, Col 7 - Style/EmptyLineBetweenDefs - Use empty lines between method definitions.
• ❗ - Line 12, Col 7 - Style/SingleLineMethods - Avoid single-line method definitions.
• ❗ - Line 146, Col 21 - Style/BlockDelimiters - Avoid using {...} for multi-line blocks.
• ❗ - Line 7, Col 7 - Style/SingleLineMethods - Avoid single-line method definitions.

[djberg96]

Upon further review I'm going to just modify the refresh code to pass a string.