lint: update ignorePatterns

[vince-fugnitto]

Bug Description:

The ignorePatterns for eslint are incorrect and mean that our own theia.d.ts and theia-proposed.d.ts files for instance are never linted causing issues, and unnecessary changes during pull-request which then need to be fixed such as #8629.

theia/configs/base.eslintrc.json

Lines 21 to 24 in 7544095

	"ignorePatterns": [
	"node_modules",
	"*.d.ts"
	]

We should update the ignorePatterns to instead exclude all content under lib folders.