parser: replace dynamic_cast with is_type method

The dynamic_cast operator is slow as it needs to look at RTTI information and even does some string comparisons, especially in deep hierarchies like the one for Node. Profiling with callgrind showed that dynamic_cast can eat a huge portion of the running time, as it takes most of the time that is spent in the simplify_tree() function. For some complex profiles, the number of calls to dynamic_cast can be in the range of millions.

This commit replaces the use of dynamic_cast in the Node hierarchy with a method called is_type(), which returns true if the pointer can be casted to the specified type. It works by looking at a Node object field that is an integer with bits set for each type up in the hierarchy. Therefore, dynamic_cast is replaced by a simple bits operation.

This change can reduce the compilation times for some profiles more that 50%, especially in arm/arm64 arch. This opens the door to maybe avoid "-O no-expr-simplify" in the snapd daemon, as now that option would make the compilation slower in almost all cases.

This is the example profile used in some of my tests, with this change the run-time is around 1/3 of what it was before on an x86 laptop:

profile "test" (attach_disconnected,mediate_deleted) {
dbus send
    bus={fcitx,session}
    path=/inputcontext_[0-9]*
    interface=org.fcitx.Fcitx.InputContext
    member="{Close,Destroy,Enable}IC"
    peer=(label=unconfined),
dbus send
    bus={fcitx,session}
    path=/inputcontext_[0-9]*
    interface=org.fcitx.Fcitx.InputContext
    member=Reset
    peer=(label=unconfined),
dbus receive
    bus=fcitx
    peer=(label=unconfined),
dbus receive
    bus=session
    interface=org.fcitx.Fcitx.*
    peer=(label=unconfined),
dbus send
    bus={fcitx,session}
    path=/inputcontext_[0-9]*
    interface=org.fcitx.Fcitx.InputContext
    member="Focus{In,Out}"
    peer=(label=unconfined),
dbus send
    bus={fcitx,session}
    path=/inputcontext_[0-9]*
    interface=org.fcitx.Fcitx.InputContext
    member="{CommitPreedit,Set*}"
    peer=(label=unconfined),
dbus send
    bus={fcitx,session}
    path=/inputcontext_[0-9]*
    interface=org.fcitx.Fcitx.InputContext
    member="{MouseEvent,ProcessKeyEvent}"
    peer=(label=unconfined),
dbus send
    bus={fcitx,session}
    path=/inputcontext_[0-9]*
    interface=org.freedesktop.DBus.Properties
    member=GetAll
    peer=(label=unconfined),
dbus (send)
    bus=session
    path=/org/a11y/bus
    interface=org.a11y.Bus
    member=GetAddress
    peer=(label=unconfined),
dbus (send)
    bus=session
    path=/org/a11y/bus
    interface=org.freedesktop.DBus.Properties
    member=Get{,All}
    peer=(label=unconfined),
dbus (receive, send)
    bus=accessibility
    path=/org/a11y/atspi/**
    peer=(label=unconfined),
dbus (send)
    bus=system
    path=/org/freedesktop/Accounts
    interface=org.freedesktop.DBus.Introspectable
    member=Introspect
    peer=(label=unconfined),
dbus (send)
    bus=system
    path=/org/freedesktop/Accounts
    interface=org.freedesktop.Accounts
    member=FindUserById
    peer=(label=unconfined),
dbus (receive, send)
    bus=system
    path=/org/freedesktop/Accounts/User[0-9]*
    interface=org.freedesktop.DBus.Properties
    member={Get,PropertiesChanged}
    peer=(label=unconfined),
dbus (send)
    bus=session
    interface=org.gtk.Actions
    member=Changed
    peer=(name=org.freedesktop.DBus, label=unconfined),
dbus (receive)
    bus=session
    interface=org.gtk.Actions
    member={Activate,DescribeAll,SetState}
    peer=(label=unconfined),
dbus (receive)
    bus=session
    interface=org.gtk.Menus
    member={Start,End}
    peer=(label=unconfined),
dbus (send)
    bus=session
    interface=org.gtk.Menus
    member=Changed
    peer=(name=org.freedesktop.DBus, label=unconfined),
dbus (send)
    bus=session
    path="/com/ubuntu/MenuRegistrar"
    interface="com.ubuntu.MenuRegistrar"
    member="{Register,Unregister}{App,Surface}Menu"
    peer=(label=unconfined),
}