Implement StringBuilder::append_option

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
I am frustrated when trying to build StringArrays using the StringBuilder.

Specifically, yhere are some places I have to / find it more convenience to use a builder (rather than the From impl) to build StringArrays, such as https://github.com/influxdata/influxdb_iox/blob/main/server/src/db/system_tables.rs#L125 where we are building system tables in IOX

With PrimitiveArrayBuilder based builders such as UInt64Builder, I can use the append_option function in the following way:

int_builder.append_option(size)?;

Which is 👍

However, since there is no corresponding append_option on GenericStringBuilder I have have to do something this which takes more time and is 👎

                if let Some(v) = column.stats.min_as_str() {
                    min_values.append_value(v)?;
                } else {
                    min_values.append(false)?;
                }

Describe the solution you'd like
Add a function StringBuilder::append_option that takes Option<AsRef<str>>

pub fn append_option(&mut self, v: Option<AsRef<str>) -> Result<()> {
...
}

Describe alternatives you've considered
Continued frustration :)

Additional context
Add any other context or screenshots about the feature request here.

[tzzed]

Can I take this one ?

[alamb]

@tzzed that would be great!