typedoc: fix docs for @theia/plugin

[vince-fugnitto]

What it does

Fixes: #10227

The pull-request fixes the generated typedoc documentation for the @theia/plugin extension including theia.d.ts and theia-proposed.d.ts following a breaking change in typedoc regarding modules:

Version 0.20 completely reworks how documentation is generated by TypeDoc. In previous versions, there was --mode file and --mode modules, which documented files according to their content on the filesystem. This worked reasonably well before ES modules were commonly used, but was insufficient for the modern ecosystem. In 0.20, TypeDoc documents your project according to what you export.

How to test

1, confirm that plugins still work correctly
2. confirm that typings for theia.d.ts and theia-proposed.d.ts works correctly
3. performing a yarn docs should now generate the typedoc correctly for @theia/plugins (both theia.d.ts and theia-proposed.d.ts combined) - note export NODE_OPTIONS=--max-old-space-size=8196 may be necessary:

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

Signed-off-by: vince-fugnitto [email protected]

[vince-fugnitto]

@tsmaeder did you have any feedback of how we now generate the typedocs for @theia/plugin?

[vince-fugnitto]

Ping :)

[tsmaeder]

The doc for the plugins package now generates fine.