automatically update the baseline file when baselined errors are removed and no new errors are added

[DetachHead]

in basedpyright, the baseline file is automatically updated by both the language server (when a file is saved) and the CLI (when running basedpyright even without the --write-baseline argument) if the following conditions are true:

• the number of baselined errors goes down
• no new errors are reported and no baselined errors are resurfaced

(more info)

this means the user doesn't have to manually update the baseline file unless they are explicitly baselining new errors. this reduces the risk of the baseline file becoming outdated, which could potentially result in errors that were previously removed unintentionally resurfacing in the future without being reported.

[connernilsen]

This should be completed as part of 6f531ce. I expect it to be available in the upcoming 1.4.0-dev.3 release