rtla: backport fixes and enhancements

JIRA: https://issues.redhat.com/browse/RHEL-50869

List of upstream commits backported:

2201aea114d4c rtla: Make doc build optional  
6127383217741 Documentation: Add tools/rtla timerlat -u option documentation  
a23c05fd76cf4 tools/rtla: Add -U/--user-load option to timerlat  
5f0769331a965 rtla/timerlat: Simplify "no value" printing on top  
a40e5e4dd0207 rtla/auto-analysis: Replace \t with spaces  
f5c0cdad6684a rtla/timerlat: Use pretty formatting only on interactive tty  
285dcb7665ae8 rtla/timerlat: Add a summary for top mode  
1462501c7a8d5 rtla/timerlat: Add a summary for hist mode  
cdbf71962bb07 rtla: Add the --warm-up option  
01b05fc0e5f3a rtla/timerlat: Fix histogram report when a cpu count is 0  
842fc5b87a505 rtla: Fix -t\--trace[=file]  
59237b0c962e8 rtla/osnoise: Use pretty formatting only on interactive tty  
587f05a88bd49 rtla/osnoise: Better report when histogram is empty  
c40583e19eeba rtla/osnoise: set the default threshold to 1us  

Signed-off-by: Luis Claudio R. Goncalves lgoncalv@redhat.com