Change return value of aeTimeProc callback function to long long.

[Shivshankar-Reddy]

moduleTimerHandler is aeTimeProc handler and event loop gets created with this. However, found that the function return type is int but actually returns "long long" value(i.e., next_period). and return value being assigned to int variable in processTimeEvents(where time events are processed), this might cause an overflow of the timer values. So changed the return type of the function to long long. And also updated other callback function return type to be consistent.

I found this when I was checking functions reported in #1054 issue stacktrace. (FYI, this is just to update the return type to be consistent and it will not the fix for the issue reported)

[codecov]

Codecov Report

Attention: Patch coverage is 80.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 70.62%. Comparing base (4593dc2) to head (dda50af).

Files with missing lines	Patch %	Lines
src/module.c	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           unstable    #1057      +/-   ##
============================================
+ Coverage     70.45%   70.62%   +0.16%     
============================================
  Files           114      114              
  Lines         61672    61671       -1     
============================================
+ Hits          43451    43553     +102     
+ Misses        18221    18118     -103     

Files with missing lines	Coverage Δ
src/ae.c	74.90% <100.00%> (ø)
src/evict.c	98.86% <100.00%> (+0.75%)	⬆️
src/server.c	88.59% <100.00%> (-0.04%)	⬇️
src/valkey-benchmark.c	57.66% <100.00%> (ø)
src/module.c	9.64% <0.00%> (+<0.01%)	⬆️

... and 17 files with indirect coverage changes