Support config files located in nested directories

[tatomyr]

What should we improve?

Currently we only support redocly.yaml file located in the root folder as the Redocly config file for VS Code.
We want to allow using different config files (similarly as we do in Redocly CLI using --config option).

How should we improve it?

We could either:

• Resolve workspace configs(depending on the monorepo structure), see this
• Resolve current closest redocly.yaml file
• Allow users to provide path to a specific config file (e.g. through a config dialog window), see this

Why should we improve it?

Users might use monorepo structure (or any other complex file structure).

Describe alternatives you've considered

Doing nothing. Users may move their redocly.yaml files to the root level (or use a symlink to the actual config file).

[lornajane]

Adding that we have something similar in other projects that might inform our approach (internal link with apologies to external contributors!) https://github.com/Redocly/redocly/pull/3252

[duncanbeevers]

This seems like a duplicate of #37
Also similar to #16

[tatomyr]

@duncanbeevers they are related. Actually, this issue was for gathering all possible solutions into one and discuss what approach is better. I'll update the description, thanks.