Fix unstable block cut process

[hata6502]

Currently, the block cut process (ctrl + x) has a weakness of maintainability.
If use await in async function BlockSelection.copySelectedBlocks, cut process doesn't copy block data.
Because BlockManager.removeSelectedBlocks() is proceeded before BlockSelection.copySelectedBlocks.
This is the unstable async function usage.

Reproduction code: src/components/modules/blockSelection.ts

  public async copySelectedBlocks(e: ClipboardEvent): Promise<void> {
    await 1;

Please check: #1485