chore(toolkit): new and improved stack selection

[mrgrain]

Reason for this change

New unified, public stack selector interface. This was previously a mix of StackSelector and options.
It was also very hard to follow.

Summary of existing usage

## Stacks for list: diff and defineEnvironments

ALL+

=> ALL, error when none exists

- fail if no stacks at all
- Always ALL stacks

## listStacks.ts: Not Selector

ALL+, MATCH

=> ALL, or match by pattern with upstream

- fail if no stacks at all
- if patterns that, otherwise ALL
- Always extend Upstream

## Single: Not a Selector, used by metadata

MUST_MATCH_ONE

=> Exactly 1, matched by pattern, errors for various out of bounds

- fail if no stacks at all
- single pattern
- no extend, no default
- Custom: Exception if more than 1
- Via stack collection: will fail if not at least 1
  
## Destroy: Selector, used by: Destroy in extension Deploy

From deploy: Exactly 1 matched by pattern, exclusive

  MUST_MATCH_ONE

From destroy: many is fine

  ALL+, MUST_MATCH, ONLY_ONE

  Bug: if no top level stacks and --all

  cdk destroy --all vs cdk destroy "*/*"
  No stack found in the main cloud assembly. Use "list" to print manifest
  Are you sure you want to delete: LocalStage/NetworkStack, DevStage/NetworkStack (y/n)? n

  Bug:
    cdk destroy unknown
    Are you sure you want to delete:  (y/n)?

Selected:
 | MAIN (not empty, extended)
 | MATCH (can be empty, extended)
 | EXACTLY ONE

- fail if no stack at all
- maybe MAIN, with throw
- otherwise patterns
- otherwise exactly 1
- extends both
- can be matching none

## Diff: Selector, used by: Diff, Synth

Wants: at least 1

Possible bug: synth/diff if no top-level and no patterns

Auto:
 | MATCH (extended, must match)
 | MAIN (not empty, not extended)

- fail if no stack at all
- never all top-level
- pattern if provided (extended)
- otherwise Main (not extended)
- Custom: Not none if patterns

### Diff

ALL+, MUST_MATCH, ONLY_ONE

  Wants Exactly 1 of template path
  Bug?: When top-level is empty
    cdk diff "*/*" -> finds both
    cdk diff "*" -> finds none
    cdk diff -> 0 stacks with differences (bug!!!)

### Synth

  ALL+, MUST_MATCH

  More than one doesn't really matter
  Bug if top-level is empty
    Supply a stack id () to display its template. -> list in () is empty

## Deploy: Selector, used by: Deploy, Rollback, Import

- Custom: Not none if patterns

### Deploy

ALL+, MAIN+, MUST_MATCH, ONLY_ONE

Bug: Empty top level and "cdk deploy --all"

Wants: at least 1

- OPTION: fail if no stack at all
- OPTION: Extends
- selector: all or patterns or exactly 1
- Custom: Not none

### Rollback

ALL+, MAIN+, MUST_MATCH, ONLY_ONE

Wants: at least 1

- fail if no stack at all
- selector: all or patterns or exactly 1
- no extend
- Custom: Not none

### Import

MUST_MATCH_ONE, ONLY_ONE

Wants: Exactly 1

- fail if no stack at all
- selector: all or patterns or exactly 1
- no extend
- Custom: more then one

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

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