This CL implements 3 new operations:
```
ALTER TABLE tbl ADD TEMPORARY PARTITION ...;
ALTER TABLE tbl DROP TEMPORARY PARTITION ...;
ALTER TABLE tbl REPLACE TEMPORARY PARTITION (p1, p2, ...);
```
User manual can be found in document:
`docs/documentation/cn/administrator-guide/alter-table/alter-table-temp-partition.md`
I did not update the grammar manual of `alter-table.md`.
This manual is too confusing and too big, I will reorganize this manual after.
This is the first part to implement the "overwrite load" feature mentioned in issue #2663.
I will implement the "load to temp partition" feature in next PR.
This CL also add GSON serialization method for the following classes (But not used):
```
Partition.java
MaterializedIndex.java
Tablet.java
Replica.java
```
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