Implement access rank select operators

[kitsuyui]

Implementation of #50 .

• access: Access the specified position in the bit sequence and get the value of the bit.
• rank: Count how many times a specific bit appears up to the specified position.
  • rank_0(i): Count how many times 0 appears up to the i-th position.
  • rank_1(i): Count how many times 1 appears up to the i-th position.
  • rank(i, bit): Count how many times bit appears up to the i-th position.
  • rank_range_0(i, j): Count how many times 0 appears between the i-th and j-th positions.
  • rank_range_1(i, j): Count how many times 1 appears between the i-th and j-th positions.
  • rank_range(i, j, bit): Count how many times bit appears between the i-th and j-th positions.
• select: Find the position where the specified number of bits appear.
  • select_0(k): Find the position where the k-th 0 appears.
  • select_1(k): Find the position where the k-th 1 appears.
  • select(k, bit): Find the position where the k-th bit appears.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (14e7652) to head (2ace204).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##              main       #51    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files            3         3            
  Lines          889       994   +105     
==========================================
+ Hits           889       994   +105     

Flag	Coverage Δ
unittests	100.00% <100.00%> (ø)

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.