chore: conservatively use log::info instead of println for some expressions

[kevaundray]

Description

If you want to see info level logs, you can do NOIR_LOG=info nargo compile by default if that environment variable is not set, then it will only print out error level logs

Problem*

Resolves

Summary*

Additional Context

Documentation*

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PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[kevaundray]

I'll open an issue to standardize the categories of logging we have -- some logging like printing out ACIR should be done using println, though for things like "Constraint system successfully built" its a bit trickier because its informational (we don't want it info level logs to be printed out by default), but we also want it to be printed out to tell the user that their program was built successfully

[kevaundray]

There might be something inherently wrong with my assumption in that we want things like "constraint system built successfully" to always be printed out -- I vaguely remember an issue where someone said that it was not easy to see what had happened.

Another solution is to just create another logging level "feedback" and put these under that category

[TomAFrench]

I'm ok with this. I'm a little concerned about hiding some of the warnings related to interacting with backends by default but we can see how that goes to see if we get a resurgence of user questions.

[jfecher]

I'm alright with this for now as well. We can re-evaluate it later if needed