Add Filesize type (#14369)

# Description
Adds a new `Filesize` type so that `FromValue` can be used to convert a
`Value::Filesize` to a `Filesize`. Currently, to extract a filesize from
a `Value` using `FromValue`, you have to extract an `i64` which coerces
`Value::Int`, `Value::Duration`, and `Value::Filesize` to an `i64`.

Having a separate type also allows us to enforce checked math to catch
overflows. Similarly, it allows us to specify other trait
implementations like `Display` in a common place.

# User-Facing Changes
Multiplication with filesizes now error on overflow. Should not be a
breaking change for plugins (i.e., serialization) since `Filesize` is
marked with `serde(transparent)`.

# Tests + Formatting
Updated some tests.

crates/nu-command/src/database/values/sqlite.rs

@@ -421,7 +421,7 @@ pub fn value_to_sql(value: Value) -> Result<Box<dyn rusqlite::ToSql>, ShellError
         Value::Bool { val, .. } => Box::new(val),
         Value::Int { val, .. } => Box::new(val),
         Value::Float { val, .. } => Box::new(val),
-        Value::Filesize { val, .. } => Box::new(val),
+        Value::Filesize { val, .. } => Box::new(val.get()),
         Value::Duration { val, .. } => Box::new(val),
         Value::Date { val, .. } => Box::new(val),
         Value::String { val, .. } => Box::new(val),