Fix issues with infered_from and add checks for infered_from and depends_on that are strings

[jenshnielsen]

Fixes #1448

Perform db upgrade to correct:

• infered_from was passed as a string not a list of strings
• infered_from was not handled correctly for parameters that were neither deps nor dependents
  In addition:
• Add logic to catch infered_from and depends_on being passed as a string.
• move db generation scripts to their own repo to disentangle qcodes git hash from the code using it. Otherwise it is very painful to change test fixtures for older db versions

As noted below I have not found a good way to get mypy to catch this kind of error.
You cannot use List[Union[ParamSpec, Str]] as list is an invariant type python/mypy#3351, the current type checking does not catch is since str in it self is a Sequence

@WilliamHPNielsen could you do a review

[codecov]

Codecov Report

Merging #1453 into master will increase coverage by 0.06%.
The diff coverage is 93.33%.

@@            Coverage Diff             @@
##           master    #1453      +/-   ##
==========================================
+ Coverage   73.79%   73.86%   +0.06%     
==========================================
  Files          92       92              
  Lines       10374    10410      +36     
==========================================
+ Hits         7656     7689      +33     
- Misses       2718     2721       +3

[astafan8]

Great!

[astafan8]

• And a test for ParamSpec?
• And what about the need for another db upgrade that fixes the outcome of _2to3_get_paramspecs? Or shall we just do it via a fix_* function?
• Also, what to do with type declarations so that mypy catches this?

[jenshnielsen]

• Agree on the test.
• I think we need an upgrade. We can perform the fix now because we still have the redundant information
  in the other table but once we do the upgrade to drop that table this needs to be fixed beforehand. I.e in a previous upgrade. If it's in a fix we may not catch all instances before doing the dropping upgrade.

Mypy:

I expected that

S = TypeVar('S')
Listuple = Union[List[S], Tuple[S, ...]]

But that does not seem to be that simple.

[jenshnielsen]

You cannot meaningfully use a List of a Union unfortunately python/mypy#3351

[Dominik-Vogel]

Great work!

[WilliamHPNielsen]

Modulo a few comments above, this looks ready.