Implement unary minus operator

[totem3]

This Pull Request closes goccy/bigquery-emulator#217

I added a unary minus operator because it was not implemented before.
As tested here, It seems to work fine with number literals, but using - on columns causes an error as described in the linked issue.

In this PR, I implemented the unary minus operator. It is basically the same as the SAFE_NEGATE function, as shown in the link below. What different is, an exception occurs when there's an overflow.
https://cloud.google.com/bigquery/docs/reference/standard-sql/mathematical_functions#safe_negate

out of scope

This unary minus operator implementation uses SAFE_NEGATE inside, but do not change SAFE_NEGATE behaviour. Currently, SAFE_NEGATE has some incompatibilities. For example,

• Given math.MinInt64, it returns an unexpected value on ubuntu. (expected 9223372036854775807 but returns -9223372036854775808)
• Given NaN, NaN is expected but it returns nil
• Given a large BigNumeric, it returns an unexpected value.

[totem3]

This error message follows the error message format used by BigQuery:

 cat <<QUERY | bq query --nouse_legacy_sql --project_id myProject
with x as (select -9223372036854775808 as v union all select null) select -v from x
QUERY
Error in query string: Error processing job 'myProject:bqjob_r79f8300c97a6ae52_0000018ec5362324_1': int64 overflow: --9223372036854775808