feat: check token usage in dry_run mode

[sigoden]

In command mode:

aichat --dry-run -r coder async sleep function in js
>>> The following message consumes 59 tokens.
I want you to act as a senior programmer.  I want you to answer only with the fenced code block. I want you to add an language identifier to the fenced code block. Do not write explanations.

async sleep function in js

In chat mode:

coder〉.set dry_run true

coder〉async sleep function in js
>>> The following message consumes 59 tokens.
I want you to act as a senior programmer.  I want you to answer only with the fenced code block. I want you to add an language identifier to the fenced code block. Do not write explanations.

async sleep function in js