Lazy serve: Rebuild current opened pages on add/remove page

[ryoarmanda]

What is the purpose of this pull request?

• Documentation update
• Bug fix
• Feature addition or enhancement
• Code maintenance
• Others, please explain:

Follow up on #1513 (ref: #1513 (comment)).

After multi-tab development is established, the add/remove page flow has yet to be updated to use the current opened pages. Currently it is still rebuilding only the current viewed page.

Overview of changes:

• Modified rebuildPageBeingViewed to adopt the page generation tasks flow
• Changed the call of rebuildPageBeingViewed on rebuildSourceFiles to use Site.currentOpenedPages

Another problem arises, as on rebuildSourceFiles, the line after is a call to lazyBuildAllPagesNotViewed, which tests the pages against Site.currentPageViewed, so toRebuild will be refilled with almost every page, which will trigger another rebuild once live-reload starts. So, I also:

• Modified lazyBuildAllPagesNotViewed to use a supplied viewedPages and test the pages against that instead
• Modified any call to the above function appropriately, e.g. on lazyBuildSourceFiles to only use the current viewed page, on rebuildSourceFiles to use the current opened pages.

Anything you'd like to highlight / discuss:

• This PR only aims to adapt the add/remove flow to use the current opened pages, so the behaviour of add/remove flow is still kept as is. That means, the issue stated in Enhance regeneration of pages during live preview #1543 still exists for now.

Testing instructions:

With the default template from markbind init:

• markbind serve -o
• Aside from the index page, open another page on a new tab
• Add a new page (easy way is to duplicate one of the files in contents)
• Observe in the logs that both the pages opened are rebuilt

Proposed commit message: (wrap lines at 72 characters)
Lazy-serve: Rebuild opened pages on add/remove page

With the addition of the multi-tab development flow, single-page serve
can keep track of all opened pages instead of a single currently
viewed page. This flow is already adopted in page edit events,
but it has yet to be adopted in page addition or removal.

Let's adopt the multi-tab development mechanism on the page addition' +
and removal flow.

---

Checklist: ☑️

• Updated the documentation for feature additions and enhancements
• Added tests for bug fixes or features
• Linked all related issues
• No blatantly unrelated changes
• Pinged someone for a review!

[ang-zeyu]

Thanks for the fix! Tested and works 👍

Just some nits:

[ang-zeyu]

let's move this comment to the original call site of the function since the use case is expanded

[ryoarmanda]

Right, moving this to the call site at changeCurrentPage

[ang-zeyu]

should we do:

Suggested change

	await this.rebuildPageBeingViewed(this.currentOpenedPages);
	await this._rebuildPagesBeingViewed(this.currentOpenedPages);

?

• plural for the expanded use case
• _ to use the non-delayed version (possible here?)

[ryoarmanda]

Agreed, I'll refactor the method (and related helpers) to use plural name, and use the non-delayed version on rebuildSourceFiles (as calls to it is already delayed)

[ang-zeyu]

Lgtm! 👍