check add and sub operation for owned fraction

[cymqqqq]

Background:
In the rgb21 contract, we have error fractionOverflow "The amount of token fractions in outputs exceeds 1", so I think maybe we should have a check add/sub-operation to check if or not the owned fraction is overflow(or the other fraction checks for add/sub-operation), also we can make a change for the allocation. It's similar to the rgb20 amount.

Description:

add check_add, check_sub, check_addassign, check_subassign, and other methods for the Ownedfraction.

[codecov]

Codecov Report

Attention: Patch coverage is 75.86207% with 21 lines in your changes missing coverage. Please review.

Project coverage is 17.6%. Comparing base (1c5b910) to head (7f637c6).
Report is 4 commits behind head on master.

Files	Patch %	Lines
invoice/src/data.rs	75.9%	21 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #229     +/-   ##
========================================
+ Coverage    17.0%   17.6%   +0.5%     
========================================
  Files          37      37             
  Lines        7379    7535    +156     
========================================
+ Hits         1257    1323     +66     
- Misses       6122    6212     +90     

Flag	Coverage Δ
rust	17.6% <75.9%> (+0.5%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[cryptoquick]

Love the tests... It's also funny to see codecov flag tests as untested

[dr-orlovsky]

ACK 7f637c6