feat(llm): add support for parsing secret vault (#200)

Signed-off-by: Aaron Pham <contact@aarnphm.xyz>

lua/avante/providers/gemini.lua

@@ -1,5 +1,4 @@
 local Utils = require("avante.utils")
-local Config = require("avante.config")
 local P = require("avante.providers")
 
 ---@class AvanteProviderFunctor
@@ -7,10 +6,6 @@ local M = {}
 
 M.api_key_name = "GEMINI_API_KEY"
 
-M.has = function()
-  return os.getenv(M.api_key_name) and true or false
-end
-
 M.parse_message = function(opts)
   local code_prompt_obj = {
     text = string.format("<code>```%s\n%s```</code>", opts.code_lang, opts.code_content),
@@ -68,7 +63,7 @@ M.parse_curl_args = function(provider, code_opts)
       .. "/"
       .. base.model
       .. ":streamGenerateContent?alt=sse&key="
-      .. os.getenv(base.api_key_name or M.api_key_name),
+      .. provider.parse_api_key(),
     proxy = base.proxy,
     insecure = base.allow_insecure,
     headers = { ["Content-Type"] = "application/json" },