feat: Decouple Modal State from Core

[lewis-sqa]

Description

• Decoupled Modal specific state to use local variables and made an attempt at "routing".
• Added back on and off for networkChanged scenario.
• Added a custom error to signal cases such as wallet not installed.
• Modified the Ledger view to have a back button instead of dismiss.
• Moved show and hide methods to the modal "package" and refactored the directory structure.
• Moved options out of state.
• Removed restApiUrl from Network. Doesn't support betanet and requires more than just the URL to function (e.g. database password etc).
• Realigned Angular example from feat: Expose State Methods for Modal UI (inc. Major API Changes) #243.

Links

• Jira Story: https://nearinc.atlassian.net/browse/SQAC-107

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Type of change. This type of change is the main reason for the PR.

• FIX - a PR of this type patches a bug.
• FEATURE - a PR of this type introduces a new feature.
• BUILD - a PR of this type introduces build changes.
• CI - a PR of this type introduces CI changes.
• DOCS - a PR of this type introduces DOCS improvement.
• STYLE - a PR of this type introduces style changes.
• REFACTOR - a PR of this type introduces refactoring.
• PERFORMANCE - a PR of this type introduces performance changes.
• TEST - a PR of this type adds more tests.
• CHORE - a PR introduces other changes than the specified above.

Breaking changes

• BREAKING CHANGE - SPECIFY: _______
• NO BREAKING CHANGE - this PR doesn't contain any breaking changes and it's backwards compatible

The base branch was changed.