fix(find): Use full path instead of real path to avoid symlinks

[bltavares]

When a respository is in a symlink-ed path (eg: larger hard-drive for projects w/ small SDD for OS), calling nio.uv.fs_realpath will perform symlink resolution.

neotest/lua/neotest/lib/file/init.lua

Line 233 in f6048f3

local err, real = nio.uv.fs_realpath(path)

Given the following scenario, nvim will run buffers with the home-dir path, instead of the resolved symlink path.

ln -s $HOME/projects /mnt/largehdd/projets
cd $HOME/projects/my_project
nvim .

Then, the following lua code will result on 2 different filenames.

local path_name = vim.api.nvim_buf_get_name(0) -- /home/me/projects/my_project/src/lib.rs
neotest.lib.files.path.real(path_name) -- /mnt/largehdd/projects/my_project/src/lib.rs

When sending the fully resolved symlinked path to a plugin, the path_name on the plugin will not match any of the path names of buffers, if they perform a search or use an external process.

This causes issues on rustaceanvim LSP-based test detection, which requires the file to be on the root of the LSP runner directory, and thus, the file_path sent is rejected.

This commit changes the login of neotest.lib.files.path.real to use the vim function for resolving the full path name, followed by an exists check, as there is 1 function usage that requires the error checking present.

Now, the following code is the same, and resolves the No tests found! when running :Neotest run file using rustaceanvim on a symlinked project folder (I know, niche...).

local path_name = vim.api.nvim_buf_get_name(0) -- /home/me/projects/my_project/src/lib.rs
neotest.lib.files.path.real(path_name) -- /home/me/projects/my_project/src/lib.rs

[rcarriga]

LGTM thanks for the PR!