Add Implementation of L1 arrow compaction

[gernest]

Closes #433

[gernest]

Parts are not guaranteed to have the same number of columns( when dyncamic columns are involved). For each compaction call we collect all columns observed across all parts. For dynamic columns, to ensure all columns have the same number of rows, we fill them with nulls when they are not found in a part.

Initially I had thought since we expect parts to be sorted , then merging them should be enough. However, I have doubts about this.

• We support multiple columns sort (including dynamic columns), the new part will contain nulls in no guaranteed order which messes up sorting expectation.
• We operate under assumptions that main sorting column behaves like timestamp which is always increasing. When using different main sorting column. It doesn't matter much if the part was sorted before. New record must be sorted for sorting to make sense.

[gernest]

Seems to be bigger than I anticipated. Closing this for now, will focus on smaller patches.