feat: Introduce alter parallelism

[shanicky]

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What's changed and what's your intention?

second part of #13954

This PR introduces the syntax ALTER TABLE/MATERIALIZED VIEW/SINK table_name SET PARALLELISM = AUTO/1,2,3…, following which the PARALLELISM status of a table can be observed within the internal rw_table_fragments table.

Altering a streaming job to AUTO will expand its degree of parallelism to encompass all available units, whereas setting it to a fixed number will lock the job’s parallelism at that specific figure. Setting it to 0 is equivalent to AUTO.

With the enable_automatic_parallelism_control option activated in the meta configuration, the addition of new compute nodes will automatically trigger an adjustment in parallelism.

Streaming jobs in AUTO mode will automatically be scaled up to include new compute nodes, whereas jobs in fixed mode will undergo a rebalance while maintaining the set level of parallelism.

dev=> set streaming_parallelism = 3;
SET_VARIABLE
dev=> create table t(v int);
CREATE_TABLE
dev=> select fragment_id, parallelism from rw_fragments;
 fragment_id | parallelism
-------------+-------------
           1 |           3
           2 |           3
(2 rows)

dev=> alter table t set parallelism = 8;
ALTER_TABLE
dev=> select fragment_id, parallelism from rw_fragments;
 fragment_id | parallelism
-------------+-------------
           1 |           8
           2 |           8
(2 rows)

dev=> alter table t set parallelism = auto;
ALTER_TABLE

dev=> select fragment_id, parallelism from rw_fragments;
 fragment_id | parallelism
-------------+-------------
           1 |          12
           2 |          12
(2 rows)

For the table we talked about before, we’re gonna treat it as custom by default to make sure it fits in okay. If you need to, you can switch it over to 'auto' or 'fixed' yourself to get that automatic control for how many things run at once, but that's only if the switch is turned on.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• All checks passed in ./risedev check (or alias, ./risedev c)

Release note

If this PR includes changes that directly affect users or other significant modifications relevant to the community, kindly draft a release note to provide a concise summary of these changes. Please prioritize highlighting the impact these changes will have on users.

Add alter parallelism syntax so that users can control the degree of parallelism for the targeted streaming job.

[yezizp2012]

LGTM, please add some details for this syntax in Release Note section.