> GetFirstStoredBlock is generalized to check for any data status with a
> status mask that needs to be passed as a parameter. To reflect this the
> function is also renamed to GetFirstBlock.
>
> Co-authored-by: stickies-v <stickies-v@protonmail.com>
In our codebase the status mask is a private member of `BlockStatus`, but we can achieve the same thing by passing a test function that takes a `BlockStatus` and returns a `bool`.
```
Core -> Bitcoin ABC
GetFirstBlock(upper_block, BLOCK_HAVE_DATA, &lower_block) -> GetFirstBlock(upper_block, [](BlockStatus status) {return status.hasData();}, &lower_block)
-> GetFirstBlock(upper_block, [](BlockStatus status) {return status.hasData();}, &lower_block)
GetFirstBlock(upper_block, BLOCK_HAVE_MASK, &lower_block)`
-> `GetFirstBlock(upper_block, [](BlockStatus status) {return status.hasData() && status.hasUndo();}, &lower_block)
```
This is a partial backport of [[https://github.com/bitcoin/bitcoin/pull/29668 | core#29668]]
https://github.com/bitcoin/bitcoin/pull/29668/commits/96b4facc912927305b06a233cb8b36e7e5964c08