[core] Improve GitHub label workflows

[DanailH]

This change is meant to improve the support workflow. We have:

1. Renamed support to support: StackOverflow to make it clear about what this is about. It's about fair value sharing. We give MIT components away for free. In exchange, MUI expects developers to give back by contributing. The expectation is not for maintainers to spend even more time to do others' work (when we apply this label), but for maintainers to process new contributions.
2. Renamed question to support: question. This is similar to the above, but we find the question so valuable to answer that we take it in.
3. Add a new support: commercial label. It's unlikely that the community will provide a lot of help to each other on the MUI X Pro plan, and will clearly not happen on the MUI X Premium plan. We have to take this in. However, bug reports and features requests should go to the usual channels, so we are simplifying the issue template.

[mui-bot]

These are the results for the performance tests:

Test case	Unit	Min	Max	Median	Mean	σ
Filter 100k rows	ms	151	395.8	200.6	251.3	92.543
Sort 100k rows	ms	428.2	720.3	509	556.2	103.274
Select 100k rows	ms	193.7	272.9	215	225.92	29.89
Deselect 100k rows	ms	131.1	227.4	177.2	172.54	34.501

Generated by 🚫 dangerJS against af18781

[oliviertassinari]

I would propose we keep this bot, and restructure the labels at the same time

1. support - stackoverflow. We rename support to this in the X and Core repositories. We don't provide support on MIT content. We delegate it to the community, the bot is important to save us time. With the date picker components, we will use it more often. The same way the support questions on DataGrid should use it.
2. support: question. We rename question to this in the X and Core repositories. This is so developers can ask valuable question to improve the experience with the product. Valuable is key on this one. Usually, such question turns into a bug, a docs, a discussion, an enhancement, or simply stay here close to build a knowledge base on GitHub. No bots
3. support - commercial. This will be used by all the issues open with https://github.com/mui-org/material-ui-x/blob/master/.github/ISSUE_TEMPLATE/3.pro-support.yml. No bots.

[DanailH]

I've updated this PR to handle the change of the labels, so support -> support: StackOverflow and we keep the bot. For the other support label we can think of the automation later.

[oliviertassinari]

I have updated the description and changed a few more things

[oliviertassinari]

Later on, to move to: https://mui.com/x/getting-started/support/