leverage PATH for locating local executables (#283)

1. This is a breaking change for the following servers, which will have to be
reinstalled:

 - ltex
 - clangd

2. This is a breaking change for users who reach into the default options (for
   example via server:get_default_options()) to access the `cmd` property.
   nvim-lsp-installer no longer provides the `cmd` (except in a few
   instances), but instead provides an amended PATH which allows neovim's LSP
   client to locate the locally installed executable.

   To access the `cmd`, simply access it via lspconfig instead, for example
   like so:

    local default_config = require("lspconfig.server_configurations.rust_analyzer").default_config
    print("I can now access the cmd governed by lspconfig:", default_config.cmd)

3. This is a breaking change for 3rd party use cases that makes use of the
   `executable()` APIs (e.g., `npm.executable(root_dir, "tsserver")`). The
   recommended usage is to instead to use the canonical name of the command
   ("tsserver"), while providing an amended PATH, for example:

    local npm = require("nvim-lsp-installer.installers.npm")
    local server = server.Server:new {
        ...,
        root_dir = root_dir,
        installer = npm.packages { "tsserver" },
        default_options = {
            cmd = { "tsserver" },
            cmd_env = npm.env(root_dir),
        }
    }

1 files changed, 8 insertions, 7 deletions

diff --git a/lua/nvim-lsp-installer/servers/kotlin_language_server/init.lua b/lua/nvim-lsp-installer/servers/kotlin_language_server/init.lua
index 0000917b..2d70c2b3 100644
--- a/lua/nvim-lsp-installer/servers/kotlin_language_server/init.lua
+++ b/lua/nvim-lsp-installer/servers/kotlin_language_server/init.lua
@@ -1,5 +1,5 @@
 local server = require "nvim-lsp-installer.server"
-local platform = require "nvim-lsp-installer.platform"
+local process = require "nvim-lsp-installer.process"
 local path = require "nvim-lsp-installer.path"
 local std = require "nvim-lsp-installer.installers.std"
 local context = require "nvim-lsp-installer.installers.context"
@@ -17,12 +17,13 @@ return function(name, root_dir)
             end),
         },
         default_options = {
-            cmd = {
-                path.concat {
-                    root_dir,
-                    "server",
-                    "bin",
-                    platform.is_win and "kotlin-language-server.bat" or "kotlin-language-server",
+            cmd_env = {
+                PATH = process.extend_path {
+                    path.concat {
+                        root_dir,
+                        "server",
+                        "bin",
+                    },
                 },
             },
         },