fix(provider): leave provider specifications to user (ayamir#887)

* add(settings): dont_set_python_host_prog option

* fix(provider): leave provider specifications to user

* remove unused code

---------

Co-authored-by: Jint-lzxy <50296129+Jint-lzxy@users.noreply.github.com>

lua/core/options.lua

@@ -105,19 +105,23 @@ local function load_options()
     wrapscan = true,
     writebackup = false,
   }
-  local function isempty(s)
-    return s == nil or s == ""
-  end
 
-  -- custom python provider
-  local conda_prefix = os.getenv("CONDA_PREFIX")
-  if not isempty(conda_prefix) then
-    vim.g.python_host_prog = conda_prefix .. "/bin/python"
-    vim.g.python3_host_prog = conda_prefix .. "/bin/python"
-  else
-    vim.g.python_host_prog = "python"
-    vim.g.python3_host_prog = "python3"
-  end
+	local function isempty(s)
+		return s == nil or s == ""
+	end
+	local function use_if_defined(val, fallback)
+		return val ~= nil and val or fallback
+	end
+
+	-- custom python provider
+	local conda_prefix = os.getenv("CONDA_PREFIX")
+	if not isempty(conda_prefix) then
+		vim.g.python_host_prog = use_if_defined(vim.g.python_host_prog, conda_prefix .. "/bin/python")
+		vim.g.python3_host_prog = use_if_defined(vim.g.python3_host_prog, conda_prefix .. "/bin/python")
+	else
+		vim.g.python_host_prog = use_if_defined(vim.g.python_host_prog, "python")
+		vim.g.python3_host_prog = use_if_defined(vim.g.python3_host_prog, "python3")
+	end
 
   for name, value in pairs(global_local) do
     vim.o[name] = value