More privatization, and some error helpers (#2976)

* More privatization, and some error helpers

This makes a lot more things private. Continued from #2967, fixes #2984
Adds public methods for various things.

Below is a brief summary of things available elsewhere, though this
particular set of changes may warrant a detailed section in the release notes.

 - bot.db.locale -> redbot.core.i18n.get_locale
   - Note: This one already existed.
 - bot.db.help -> redbot.core.commands.help.HelpSettings
 - bot db whitelist/blaclist? -> bot.allowed_by_whitelist_blacklist
   - This has also been made a single cannonical function for this
   purpose including check usage
 - bot color? -> bot.get_embed_color/bot.get_embed_colour
 - bot.id.api_tokens? ->

   - bot.get_shared_api_tokens
   - bot.set_shared_api_tokens
   - bot.remove_shared_api_tokens

 -bot.db.prefix -> bot.get_valid_prefixes
   - (Note: This is a wrapper around bot.get_prefix)

 Other changes include
  - removing `bot.counter` as it was never used anywhere
  - Adding properties with helpful error messages for moved and renamed
  things
  - making bot.uptime a property with an error on set
  - adding a migration to the bot config for shared_api_tokens

* Remove overly encompassing message redaction, eval is a risk, dont run in dev if you cant manage it

* address Flame's feedback

* rephrase example

* changelog extras

* You saw nothing

redbot/core/cog_manager.py

@@ -317,7 +317,7 @@ class CogManagerUI(commands.Cog):
         """
         Lists current cog paths in order of priority.
         """
-        cog_mgr = ctx.bot.cog_mgr
+        cog_mgr = ctx.bot._cog_mgr
         install_path = await cog_mgr.install_path()
         core_path = cog_mgr.CORE_PATH
         cog_paths = await cog_mgr.user_defined_paths()
@@ -344,7 +344,7 @@ class CogManagerUI(commands.Cog):
             return
 
         try:
-            await ctx.bot.cog_mgr.add_path(path)
+            await ctx.bot._cog_mgr.add_path(path)
         except ValueError as e:
             await ctx.send(str(e))
         else:
@@ -362,14 +362,14 @@ class CogManagerUI(commands.Cog):
             await ctx.send(_("Path numbers must be positive."))
             return
 
-        cog_paths = await ctx.bot.cog_mgr.user_defined_paths()
+        cog_paths = await ctx.bot._cog_mgr.user_defined_paths()
         try:
             to_remove = cog_paths.pop(path_number)
         except IndexError:
             await ctx.send(_("That is an invalid path number."))
             return
 
-        await ctx.bot.cog_mgr.remove_path(to_remove)
+        await ctx.bot._cog_mgr.remove_path(to_remove)
         await ctx.send(_("Path successfully removed."))
 
     @commands.command()
@@ -385,7 +385,7 @@ class CogManagerUI(commands.Cog):
             await ctx.send(_("Path numbers must be positive."))
             return
 
-        all_paths = await ctx.bot.cog_mgr.user_defined_paths()
+        all_paths = await ctx.bot._cog_mgr.user_defined_paths()
         try:
             to_move = all_paths.pop(from_)
         except IndexError:
@@ -398,7 +398,7 @@ class CogManagerUI(commands.Cog):
             await ctx.send(_("Invalid 'to' index."))
             return
 
-        await ctx.bot.cog_mgr.set_paths(all_paths)
+        await ctx.bot._cog_mgr.set_paths(all_paths)
         await ctx.send(_("Paths reordered."))
 
     @commands.command()
@@ -413,14 +413,14 @@ class CogManagerUI(commands.Cog):
         """
         if path:
             if not path.is_absolute():
-                path = (ctx.bot.main_dir / path).resolve()
+                path = (ctx.bot._main_dir / path).resolve()
             try:
-                await ctx.bot.cog_mgr.set_install_path(path)
+                await ctx.bot._cog_mgr.set_install_path(path)
             except ValueError:
                 await ctx.send(_("That path does not exist."))
                 return
 
-        install_path = await ctx.bot.cog_mgr.install_path()
+        install_path = await ctx.bot._cog_mgr.install_path()
         await ctx.send(
             _("The bot will install new cogs to the `{}` directory.").format(install_path)
         )
@@ -433,7 +433,7 @@ class CogManagerUI(commands.Cog):
         """
         loaded = set(ctx.bot.extensions.keys())
 
-        all_cogs = set(await ctx.bot.cog_mgr.available_modules())
+        all_cogs = set(await ctx.bot._cog_mgr.available_modules())
 
         unloaded = all_cogs - loaded