feat: provide option to start with recording page

[GitMensch]

This is a draft to showcase the working feature.

The main question is: Do we want a single option (as in this PR) that opens the recording page when no files are given (then we may want to output an error if the QStringList files is not empty); or do we want an option like "openPage" with a set of names that works in general (also for files opened, which then needs to be postponed after a possible load is done to switch from the summary page to the specified one).

... and of course I'm open to a better name than record or openPage.

after everything is clear the README will get updated as well to include the new option in the help output

[milianw]

Imo, --record sounds too similar to perf record, meaning it would expect it to directly start recording whatever else is passed after it. But this would require (much) more work, with little gain - one can just copy'n'paste the record step into a script and only visualize the data afterwards after all. That said, I'm not opposed to someone working on that if there is a desire for such functionality.

For your use-case, I think we should rather approach it differently, i.e. like you say here:

an option like "openPage" with a set of names that works in general