I've been working on streaming and pipeline interruption lately. It was
bothering me that checking ctrl+c (something we want to do often) always
requires a bunch of boilerplate like:
```rust
use std::sync::atomic::Ordering;
if let Some(ctrlc) = &engine_state.ctrlc {
if ctrlc.load(Ordering::SeqCst) {
...
```
I added a helper method to cut that down to:
```rust
if nu_utils::ctrl_c::was_pressed(&engine_state.ctrlc) {
...
```
A partial fix for #7477. `uniq` can be slow sometimes, so we should
check `ctrl-c` when it's running.
Tested on [this
file](https://home.treasury.gov/system/files/276/yield-curve-rates-1990-2021.csv),
I ran `open yield-curve-rates-1990-2021.csv | uniq` and confirmed that I
can now cancel the operation.
Future work is needed to figure out why `uniq` is so slow.
* make format filesize more flexible
* make code simpler
* finish refactor on bytes commands
* finish refactor on str commands
* fimplify code
* rename from column_paths to cell_paths
