Renames fns to get_stored_account_meta()

[brooksprumo]

Problem

Since #774, we now have get_account(), get_stored_account(), get_stored_account_meta(), and get_account_shared_data() methods, but AppendVec::get_account() returns a StoredAccountMeta. I find this a bit confusing. If we rename get_account(), I think that would help.

Summary of Changes

Renames the methods to get_stored_account_meta() and updates callers.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 91.66667% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 81.9%. Comparing base (518a5b7) to head (ee8e38e).
Report is 9 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master     #783     +/-   ##
=========================================
- Coverage    81.9%    81.9%   -0.1%     
=========================================
  Files         851      851             
  Lines      231231   231341    +110     
=========================================
+ Hits       189515   189597     +82     
- Misses      41716    41744     +28     

[jeffwashington]

lgtm