cli: Use program length for deployments instead of 2x length

[joncinque]

Problem

The default behavior for program deployments uses 2x the length of the deployed program. This behavior accommodated larger program deployments over time, but requires a greater upfront cost. With solana program extend, however, there's no need to lock up more SOL than necessary for a program.

Summary of Changes

Use the program length when deploying instead of 2x, and update the documentation to reflect that change, including how to extend a program.

There might be some overlap of changes by including the extend documentation, so let me know if you prefer that in a separate PR!

Fixes #

[pgarg66]

Looks good to me! Giving time to @CriesofCarrots to review it before approving it.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (c5d51ac) 81.8% compared to head (ff6db66) 81.8%.
Report is 7 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #34730   +/-   ##
=======================================
  Coverage    81.8%    81.8%           
=======================================
  Files         824      824           
  Lines      222725   222723    -2     
=======================================
+ Hits       182317   182356   +39     
+ Misses      40408    40367   -41     

[CriesofCarrots]

r+ nit in changelog text