Support tsconfig extends array

[Logicer16]

Fixes(if relevant):

Typescript v5 added support for using an array to specify multiple files to extend from. This PR updates type-coverage to support projects which use this feature.

It aims to match the behaviour of typescript in the order files are processed where, for example:

{
   "extends": ["a", "b", "c"]
}

[behaves] like extending c directly, where c extends b, and b extends a. If any fields “conflict”, the latter entry wins.

This shouldn't change functionality for when a single extends source is specified, either through a string or a single element array.

Checks

• [x] Contains Only One Commit(git reset then git commit)
• [x] Build Success(npm run build)
• [x] Lint Success(npm run lint to check, npm run fix to fix)