feat(ui-devkit): Add "exclude" option to UI extensions

[vrosa]

Context

As custom UI extensions mature, a Vendure developer might want to write unit tests or perhaps Storybook stories and choose to colocate them with the corresponding component. Currently, UI Devkit copies everything inside the extensionPath directory, which could also bring unintended files to the output.

Proposed solution

Allow developers to optionally specify files within their UI extension to be skipped during the copy process.

Description of changes

• Update @vendure/ui-devkit to support a new optional exclude property in AdminUiExtension objects, which takes a string array and works the exact same way as TypeScript's tsconfig.json counterpart.
• Update typescript-doc-parser.ts to support escaped /* tokens in comment descriptions. I decided to introduce this additional change because the best example of exclude is using a globstar pattern, which causes a multi-line comment to end. Escaping it using the same existing approach as the @ token seemed like an obvious choice, however, I'm more than happy not to include changes to that logic and use a different pattern in the exclude comment description.

[michaelbromley]

I'm very happy that you and your team are exercising the admin ui extensions heavily and finding these points to improve! Thanks again!