More privatization, and some error helpers

[mikeshardmind]

Type

• Bugfix
• Enhancement
• New feature

Description of the changes

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/blacklist? -> bot.allowed_by_whitelist_blacklist

  • This has also been made a single canonical 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
• fixing a couple prior missed bot.db -> bot._config uses

[mikeshardmind]

After some feedback from various cog creators in the discord server, there should be a few more things exposed in this PR prior to it being merged.

Will be adding those soon™️

[mikeshardmind]

This now has all the changes planned for this PR.

Some of the attributes related to help formatting should also be exposed, but this should be done with the design concerns of #2981 in mind, likely as part of those changes.

[Flame442]

Everything appears to work but I didn't do extensive edge case testing nor do I understand the internals to see any implications of these changes. I've included some recommendations for some changes to docstrings and other UX.

[Cog-CreatorsBot]

Approved by Flame#2941

[DevilXD]

It's kinda too late, but is this file supposed to be there? Doesn't it belong in the changelog folder?
https://github.com/Cog-Creators/Red-DiscordBot/blob/V3/develop/redbot/core/2976.feature.rst

EDIT: Nvm, I just saw #3019