Improve error message returned to user on invalid input (uint64)

In some cta-admin sub-commands, when sending a wrong input type, we get a message like is not a valid uint64.

Instead, we should return something more user-friendly, such as is not a valid unsigned integer. This is already done is some situations.

Example:

[root@ctacli /]# cta-admin mp ch --ap a
a is not a valid uint64:  [--archivepriority/--ap <priority_value>]

This is coded in:

cmdline/CtaAdminCmd.cpp#466:         throw std::runtime_error(value + " is not a valid uint64: " + option.help());
cmdline/CtaAdminGrpcCmd.cpp#289:     throw std::runtime_error(strValue + " is not a valid uint64: " + option.help());

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For more details check:

• https://gitlab.cern.ch/cta/operations/-/issues/1118