Positions for text, announcement, and store channels are all separate

[advaith1]

Please describe the problem you are having in as much detail as possible:
When there are channels of more than one of those 3 types in one category, they will all be separate: the first text channel will be position 0, the first announcement channel will be position 0, the second text channel will be position 1, etc.
Discord lets you mix these types and put them in any order, unlike voice channels, which must all remain at the bottom of the category.

Include a reproducible code sample here, if possible:

client.channels.cache.get('499345401766346752').position // 0
client.channels.cache.get('374925969099587584').position // 0

of course, you'll need to test with channels in a server the bot is in.

Further details:

• discord.js version: 12.0.0
• Node.js version: v12.14.1
• Operating system: Ubuntu 16.04.6
• Priority this issue should have – please be realistic and elaborate if possible: Low, not a bot-breaking issue

• I have also tested the issue on latest master, commit hash: 5b9cdc5