Comment 2 for bug 1952008

Reviewed: https://review.opendev.org/c/starlingx/config/+/819038
Committed: https://opendev.org/starlingx/config/commit/f096dcf15903a3b962182f5b85d173a0b1523dd2
Submitter: "Zuul (22348)"
Branch: master

commit f096dcf15903a3b962182f5b85d173a0b1523dd2
Author: Rafael Camargos <email address hidden>
Date: Tue Nov 23 21:18:31 2021 -0300

    Add validation of special chars on system values

    Setting a system value with special characters will get sysinv in a
    dirty state and unreachable. E.g.: `system modify -n='º'`. This is
    caused because isystem DB won't accept these special chars.

    This work adds a validation on the PATCH method of the SystemController
    blocking any special character that is not accepted.

    Test Plan:

    PASS: Verify special characters won't be accepted on system values
    PASS: Verify system installation/bootstrap executes properly
    PASS: Verify the system works properly after setting a value with any of
    the accepted characters: 'a-zA-Z0-9!@#$%^&*()_+-=[]{};:'"|,.<>/? '
    PASS: Verify system https_enabled can be properly toggled

    Closes-Bug: 1952008
    Signed-off-by: Rafael Camargos <email address hidden>
    Change-Id: I1844e6af40c7b82f2c5a6e995947b1c166f82e0d