Perform client-side validation of all Auth Tokens input to the Sentry CLI. To ensure future-compatibility, we only provide soft validation, meaning that we only print a warning message if we detect that the Auth Token is invalid – the CLI will still proceed with normal execution if the Auth Token is invalid.

Fixes GH-1859

This PR makes two improvements to the sourcemaps resolve command output:

  - The PR changes the output line and column values from zero-indexed to one-indexed values. By switching to one-indexed values, the output line and column numbers use the same scale as the input values and follow the standard convention for line and column numbers in source code files. This change fixes the off-by-one error reported in Source mapping is offset when using switch statements #1863.
  - The output text has been restructured and clarified to indicate that the sourcemap resolver locates the closest token to the line and column input that the user provides. With this change, it should be clear to users that the source and minified file line/column locations reported in the output are the locations of this nearest token that the sourcemap resolver locates. This change is specifically intended to help avoid confusion in cases where the nearest token may in a different location (perhaps even, on a different line) than the search location provided in the user's input.

Fixes GH-1863