show rent model

[rob-solana]

Problem

rent's constraints aren't intuitive

Summary of Changes

support printing out some basics of the rent model

Fixes #

[mvines]

This would make an awesome new cli subcommand: solana show-rent

[rob-solana]

This would make an awesome new cli subcommand: solana show-rent

would you rather a new RPC or augmentation of current one?

[codecov]

Codecov Report

Merging #7410 into master will decrease coverage by 0.6%.
The diff coverage is 0%.

@@           Coverage Diff            @@
##           master   #7410     +/-   ##
========================================
- Coverage    67.9%   67.2%   -0.7%     
========================================
  Files         245     245             
  Lines       57498   58018    +520     
========================================
- Hits        39044   39022     -22     
- Misses      18454   18996    +542

[mvines]

I don't see an obvious existing RPC API that we could graft onto so prolly a new one. But sombody adding a solana show-rent command isn't urgent and don't need to block this PR by any means

[rob-solana]

I don't see an obvious existing RPC API that we could graft onto so prolly a new one. But sombody adding a solana show-rent command isn't urgent and don't need to block this PR by any means

    get_minimum_balance_for_rent_exemption(&self, data_len: usize)

[garious]

Seems like a natural extension of solana fees.

[rob-solana]

#7413