Disable trimwhitespace and drawwhitespace via their configs (#1446)

Instead of completely disabling them, we now use their internal toggle.

Also moved `drawwhitespace` commands inside the plugin.

---

* Fixed bug where commands would show even when plugin was disbled. Also removed antiquated way of disabling.

* Fixed typos.

* Also moved trimwhitespace out of config, if it already has a default enabled value of false.

* Changed documentation.

* Clarified comments.

data/plugins/trimwhitespace.lua

@@ -8,7 +8,7 @@ local Doc = require "core.doc"
 ---@field enabled boolean
 ---@field trim_empty_end_lines boolean
 config.plugins.trimwhitespace = common.merge({
-  enabled = true,
+  enabled = false,
   trim_empty_end_lines = false,
   config_spec = {
     name = "Trim Whitespace",
@@ -17,7 +17,7 @@ config.plugins.trimwhitespace = common.merge({
       description = "Disable or enable the trimming of white spaces by default.",
       path = "enabled",
       type = "toggle",
-      default = true
+      default = false
     },
     {
       label = "Trim Empty End Lines",