Refactor queries && fix issues related to references

[tiensonqin]

Problem

1. can't edit and enter new blocks in the references
2. references and source blocks are not synced
3. the existing queries are verbose, it doesn't utilize datascript's recursive queries very well (although we might move to a performant way in the future)
4. to render the blocks tree, no matter it's a page or refs, a query is triggered when encountering a parent block, this not only hurts the performance but also makes the code ugly.

Goals

1. make queries simpler and easy to use
2. simplify the rendering code

Warnings, it might breaks:

1. aliases
2. block-refs data attributes

Need more thoughts

1. Should we remove blocks->vec-tree? Recursive queries already provide the tree structures, we can also use datascript's raw index API to make it faster. see Why are Datascript queries so slow? tonsky/datascript#130 (comment)

• can't edit or enter new blocks on linked references
• references and source blocks are not synced
• simplify the queries
• collapse children blocks by default, it shouldn't affects the expand/collapsed state for the source blocks
• unlinked references

[ghost]

LGTM