feature(FieldAPI): Change from touched error message and error message to error map and array of errors

[CheRayLiu]

We'd like to change our validators to return an object and array of errors to avoid UX limitations for any app that uses TanStack Form.

Quoted from @crutchcorn. Based on the changes, an example usage in our react adapter would be:

<form.Field
  name="firstName"
  children={(field) => {
    const errArr = field.state.meta.errors // Array of errors
    const errMap = field.state.meta.errorMap; // Object of errors
    const onChangeErr = errMap?.onChange; // string | undefined | null
  }}
/>

This change includes:

• Replacing FieldMeta.error with FieldMeta.errors and FieldMeta.errorMap
• Replacing FieldMeta.touchedError with FieldMeta.touchedErrors
• Updating the validation methods to accommodate those changes
• Update documentation to reflect the changes

Resolves #431

[crutchcorn]

Fantastic start! There's some super minor nitpicks here, but you're on an amazing track!

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[codecov-commenter]

Codecov Report

Patch coverage is 87.09% of modified lines.

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Files Changed	Coverage
packages/form-core/src/FormApi.ts	66.66%
packages/form-core/src/FieldApi.ts	88.46%
packages/form-core/src/utils.ts	100.00%

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