Atlas - player color not updated correctly after changing it

[elexis]

If the someone changes the playercolor in atlas, the territory color and selection ring color isn't updated until the next update.

The Player component could just broadcast a message just for this case, just like it does broadcast MT_CivChanged just for this case.

This message would also be needed to save a lot of unneeded updates in ​Phab:D623.

The CivChanged message could also be used for the rallypoint flags that depend on the civ.

[elexis]

In 19965:

Update the color of the selection ring, rallypoints and territory outline when the playercolor is changed in atlas.
Merge duplicate Selectable component playercolor code.

Differential Revision: ​https://code.wildfiregames.com/D687
Fixes #4643
Refs D623
Patch in cooperation with: Stan

[elexis]

In 20951:

Fix undefined player color errorspam in Atlas after placing an entity, changing the civ and starting the simulation following rP19965 / D623, refs #4643.

The commit had removed the fallback color as there is no traceable use case.
Copy the Player color from the old to the new player entity in ReplacePlayer before the ownership changes occur, so that it is always initialized before read.

Refs rP16092
Reported By: temple