feat: multiple backend-config inputs

[rdhar]

Note

While this is a patch release, existing PRs should be updated for consistent behaviour with plan files.

Added

• Pass in multiple comma-separated -backend-config values (thank you, @fulgas).
  E.g., arg-backend-config: encrypt=true,bucket="bucket-name",dynamodb_table="table-name".
  • This is in addition to existing support for -var, -target, and -replace comma-separated values.

Improved

• Portion of plan file artifact name is hashed with MD5 for concise, fixed-length string.
  • This is to address GitHub's 256 character limit for artifact naming.
  • As a bonus, this also masks potentially sensitive values from arg-var input.
• Documentation to include "To-Do" tasks.

To-do

• Handling of inputs which contain space(s) (e.g., working-directory: "path to/directory").
• Handling of comma-separated inputs which contain comma(s) (e.g., arg-var: token=1,2,3).

Resolves #351, #350.