Add log lines to clarify what pinning is doing

[inlined]

Per bug bash feedback, this adds logs for:

1. Explaining that pinned functions will also be deployed even if there is an --only string that does not include them
2. Explaining that run pins target the current latest revision of the Run service since we cannot deploy them with the CLI.=

[codecov-commenter]

Codecov Report

Patch coverage: 71.42% and no project coverage change.

Comparison is base (4d6da7e) 55.19% compared to head (14ba0d2) 55.20%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5787   +/-   ##
=======================================
  Coverage   55.19%   55.20%           
=======================================
  Files         329      329           
  Lines       22527    22537   +10     
  Branches     4590     4593    +3     
=======================================
+ Hits        12434    12441    +7     
  Misses       8989     8989           
- Partials     1104     1107    +3     

Impacted Files	Coverage Δ
src/deploy/hosting/prepare.ts	65.30% <71.42%> (+0.53%)	⬆️

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