Initial version of Lit adapter for Tanstack form

[Christian24]

This closes #498.

This is the first cut.

It has tests, a basic example and the base-lib, there's also Material Web Components example. I added a little QuickStart guide.

Open points:

• I am not 100% sure this is entirely type safe and I am not sure why it is not. It seems the field options passed .field() can be pretty much anything. Upon further investigation, this seems to be an issue with using an array, so maybe DeepKeys or its use is broken? @crutchcorn?

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Codecov Report

Attention: Patch coverage is 67.90123% with 26 lines in your changes are missing coverage. Please review.

Project coverage is 88.84%. Comparing base (c740617) to head (d71df41).

Files	Patch %	Lines
packages/lit-form/src/tests/simple.ts	56.52%	19 Missing and 1 partial :warning:
packages/lit-form/src/tanstack-form-controller.ts	82.85%	5 Missing and 1 partial :warning:

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Additional details and impacted files

@@                       Coverage Diff                       @@
##           array-and-provider-refactor     #577      +/-   ##
===============================================================
- Coverage                        91.18%   88.84%   -2.34%     
===============================================================
  Files                               26       28       +2     
  Lines                              726      807      +81     
  Branches                           172      185      +13     
===============================================================
+ Hits                               662      717      +55     
- Misses                              59       83      +24     
- Partials                             5        7       +2     

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[crutchcorn]

@Christian24 I just realized that we don't have a Lit adapter for TanStack Store. Is there any way we could build this and then utilize it inside of Form's Lit adapter?

That would fall more in line with other stuff

[Christian24]

@Christian24 I just realized that we don't have a Lit adapter for TanStack Store. Is there any way we could build this and then utilize it inside of Form's Lit adapter?

That would fall more in line with other stuff

I am not sure where it would be needed honestly. Where exactly are you thinking about?

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[crutchcorn]

I did not close this PR or delete the upstream branch. Instead, I merged this PR:

https://github.com/TanStack/form/pull/588

Which this PR was supposed to be based off of.

I don't know what's happened - I've pinged GH (thru private channels). In the meantime, I have a backup somewhere, luckily

EDIT: I figured out what happened and have fixed the issue manually. GH has been notified.