Add test fixture files for E2E test

[dbanck]

This should allow us to implement some scenarios like:

• Completion for a local module sources (prefix ./)
• Completion for inputs of a local module
• Go-to-definition on a local module source
• Go-to-definition on a module input
• Go-to-definition on a var.something reference
• Completion of the variable name inside the tfvars file
• Go-to-definition on the variable name inside tfvars
• Find references on the variable block

[github-actions]

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