Don't use a temporary file for tflint

[dimbleby]

Standard terraform module structure is to split files into main.tf, variables.tf, output.tf.

Current tflint linting creates a temporary file. But taking eg the main.tf in isolation prevents tflint from doing its job, ALEInfo shows output like this:

{"issues":[],"errors":[{"message":"Failed to check `azurerm_public_ip_invalid_sku` rule: Failed to eval an expression i
n /tmp/nvimcFkTcA/2/main.tf:49; Reference to undeclared input variable: An input variable with the name \"vm\" has not
been declared. This variable can be declared with a variable \"vm\" {} block."}]}

... where the vm was indeed declared, in the variables.tf file, where it should be.

Simply not using a temporary file resolves this.

[dimbleby]

Using a temporary file was deliberately introduced, at #1052.

Presumably either ALE or tflint has changed since then, the linting works fine without it now.

[dimbleby]

Ah, but then the linter become useless in a different way: tflint doesn't recurse into subdirectories. So you need to be in the working directory of the file being linted.

Therefore I've also set cwd for this linter.

[hsanson]

Change seems correct and basic testing seems to work for me.