[Feature] Add time_round builtin functions

[ccoffline]

Proposed changes

#4619
Add time_round functions that provides time_floor & time_ceil at each time unit.

Fix two related bugs.

• 【bug】timestampdiff 在某个情况下计算有误 #4618
• Fix struct TimeInterval to use int64_t instead of int32_t, in case when the second diff overflow

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [] Documentation Update (if none of the other choices apply)
• [] Code refactor (Modify the code structure, format the code, etc...)

Checklist

• I have create an issue on (Fix #ISSUE), and have described the bug/feature there in detail
• Compiling and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• If this change need a document change, I have updated the document
• Any dependent changes have been merged

Further comments

This change didn't match the style as TIMESTAMPDIFF, which has some syntactic sugar on the time units in FE. I'm not much familiar with this implementation, so I'm going to figure it out and make up for the documentation then.

[morningman]

Thanks for you PR.
Could you please add document for this new function?
under sql-reference/sql-functions/date-time-functions/

[ccoffline]

Could you please add document for this new function?
under sql-reference/sql-functions/date-time-functions/

Like I said, TIMESTAMPDIFF implementation in FE has some syntactic sugar on the time units, which combines all the functions into one. This makes the doc look much prettier.

This function set has (#4619)

7(year, month, week, day, hour, minute, second) * 2(floor, ceil) * 4([timestamp], [ts, period], [ts, origin], [ts, period, origin]) = 56 functions.

I'll try to make the doc look simple.

[ccoffline]

@morningman docs added

[morningman]

LGTM