feat: Pass fname and cwd to parse function

[mothzarella]

Both parse and fn provider functions now receive fname and cwd parameters to provide file path and working directory context.

[Copilot]

Pull request overview

This PR adds file path and working directory context to linter provider functions by passing fname and cwd parameters to both parse and fn functions. This enhancement allows custom linters to access file location information when processing lint results or generating lint output.

Changes:

• Updated lint.parse() calls to include fname and cwd parameters (lines 107, 122)
• Updated lint.fn() call to include fname and cwd parameters (line 120)

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[xiaoshihou514]

Instead of fname, would bufid be a better choice? 🤔 Seems much more natural as an api.

Could you remind me again why you need cwd?

[mothzarella]

As I wrote in the issue: "parse runs inside async.run, which means it's in a fast event context where you can't call neovim api." By passing only bufnr, you wouldn't be able to obtain the filepath that the linter is actually operating on, you'd need to call vim.api.nvim_buf_get_name(bufnr) inside the parser, which isn't allowed in that context.

Example with terraform validate -json

{
  "format_version": "1.0",
  "valid": true,
  "error_count": 0,
  "warning_count": 2075,
  "diagnostics": [
    {
      "severity": "warning",
      "summary": "Deprecated Resource",
      "detail": "This resource is deprecated...",
      "address": "module.some.module.address.abcd.name",
      "range": {
        "filename": ".terraform/modules/some.address/main.tf",
        ...
      }
    }
    ... other 2074 warnings
  ]
}

• NOTE: Without fname filtering, all 2075 warnings would show up in every buffer.

Regarding cwd: some linters output paths relative to the working directory (especially in CI or when run recursively). Having cwd available allows the parser to resolve relative paths correctly and match them against the buffer's absolute path:
local rpath = fname:sub(#cwd + 2), but you can just match fname with diagnostics.range.filename ig.

[xiaoshihou514]

How about a get state function that runs outside of the coroutine?