## Context
Currently for FDWs under integrations, editing an FDW involves tearing
it down then re-creating it - which while conveniently works has a lot
of problems like:
- Blast radius is way bigger than the edit
- Everything is recreated, including vault secrets
- Silent drops grants/comments/ownership
- Cascades on dependent objects
- Views or functions built on top of foreign tables would get dropped
along with it
Changes in this PR hence updates `getUpdateFDWSql` to diff the current
wrapper state against the form state and generate targeted `ALTER`
statements for only what actually changed
## To test
- [ ] Verify that updating an existing wrapper still works as expected
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Wrapper changes can be saved in place, including server options,
encrypted values, foreign tables, and column definitions.
* Input fields can display placeholder text, and missing server-option
values display their defaults.
* **Improvements**
* Saving is unavailable until encrypted values are ready; a waiting
message appears while they load.
* The edit panel closes after a successful save. Confirmation text
explains that table or column changes may affect dependent
functionality.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Joshen Lim
9aae037dff