Fix Serialization P1s

[camsaul]

Refactoring the serialization code pursuant to fixing these is in scope (target is 39.x for as many fixes as possible, if there is any major rework required, that will go to 40):

First

• Serialization: Nested question references questions in other collection are moved and becomes corrupted #14914
• Serialization: Dashboard cards are corrupted, when questions are outside of dashboard collection #14912
• Serialization: Click Behavior not translating entitiy ID on dump, potentially referencing wrong entities on load #14566

and then:

• Serialization dumps with static references instead of paths in 1.39.0 #15812
• Serialization dump includes Personal Collections #15120

stretch goals (not putting with checkboxes since they're stretch):

• Serialization: Snippets are not transferred correctly, leading to incorrect references and broken queries #14909
• Serialization: Objects (questions/dashboards/etc) with the same name in same collection replaces each other during dump #15285
• Serialization load-process does not update source-table in joins, leading to broken questions #15283
• Serialization doesn't update Sub-Query variable references in the editor #15051
• Serialization: Snippet folders and Collections collide on dump because of missing namespace separation #14910
• Serialization: Table columns with "Display values"="Use foreign key" not always saved during dump #15848

[jeff303]

Consolidated PR created here: #15858