Fix broken feature layout due to async race condition on getRpcDriver

[cmdcolin]

This appears to fix #2547

The summary of #2547 is that multiple rpc drivers were being created due to the async change of getDriver

This changes it back to not being an async call, but loses the storing of ipc call to userData with this

If it is needed to have userData for other purposes in the code, it could be obtained in another way?

Alternatively, we could modify this PR to try to avoid double-creation of the drivers e.g. with a promise-singleton type pattern seen elsewhere in the codebase

[codecov]

Codecov Report

Merging #2551 (0df5bce) into main (4952829) will increase coverage by 0.00%.
The diff coverage is 33.33%.

@@           Coverage Diff           @@
##             main    #2551   +/-   ##
=======================================
  Coverage   60.69%   60.70%           
=======================================
  Files         547      547           
  Lines       25582    25575    -7     
  Branches     6042     6041    -1     
=======================================
- Hits        15528    15526    -2     
+ Misses       9728     9723    -5     
  Partials      326      326           

Impacted Files	Coverage Δ
packages/core/rpc/WebWorkerRpcDriver.ts	0.00% <ø> (ø)
...ckages/development-tools/src/createRollupConfig.ts	0.00% <0.00%> (ø)
packages/core/rpc/RpcManager.ts	87.09% <66.66%> (+4.23%)	⬆️

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[garrettjstevens]

There was a version of plugin loading that saved downloaded plugin code to the userData directory, but it doesn't do that anymore, so it should be fine to get rid of this leftover bit. We can probably get rid of this handler in electron.ts, too:

jbrowse-components/products/jbrowse-desktop/public/electron.ts

Lines 316 to 318 in abedfa8

	ipcMain.handle('userData', () => {
	return userData
	})

Good catch!

[cmdcolin]

might be ok to hold onto the vestigial IPC call there...maybe it will find another use :)