V14 migration guide / breaking changes

[ankush]

Need to update docs and migration guide for breaking changes in v14.

https://github.com/frappe/frappe/wiki/Migrating-to-Version-14

• update python / system dependencies / installation | @gavindsouza
• Update JS dependenicies | @surajshetty3416 (https://github.com/frappe/frappe/wiki/Migrating-to-Version-14#dependencies)
• refactor!: frappe.db.exists #16200 | @alyf-de
• chore!: remove deprecated quaggajs based barcode scanner #17248 | @ankush
• feat(UX)!: always sharable URLs on List/Report/Kanbanview #17072 | @ankush
• fix!: block customizing select field type options #16157 | @ankush
• fix!: dont delete customizations when doctypes are deleted  #17009 | @ankush
• fix!: drop py3.7 support for v14 #15569 | @ankush
• fix!: remove dangerous "rollback_on_exception" flag #17321 | @ankush
• fix!: run synchronous background jobs directly in production #16256 | @ankush
• fix(postgres)!: transactions implementation for PostgreSQL #15495 | @ankush
• fix(ux)!: when error messages are present, supress non-error messages #16284 | @ankush
• perf!: improve document caching #17061 | @ankush
• perf!: simpler frappe.get_system_setting #16685 | @ankush
• refactor!: improve/extend log settings #17159 | @ankush
• refactor!: remove dev requirements from requirements.txt #14517 | @ankush
• refactor!: remove video plyr from default bundle #17249 | @ankush
• feat!: Added support for IS in frappe qb #16877 | @Aradhya-Tripathi
• chore: Clean up requirements #14958 | @ChillarAnand
• refactor!: Remove wrapt package #16715 | @ChillarAnand
• chore: Dead dependencies and code cleanup #13344 | @gavindsouza
• chore: Drop Data Import Legacy #13554 | @gavindsouza
• feat!: Async Document Renaming #16130 | @gavindsouza
• fix!: Allow child table naming (autoname) #16608 | @gavindsouza
• fix!: Misc fixes #15763 | @gavindsouza
• fix!: Remove dead functionality #16450 | @gavindsouza
• perf!: Pages & APIs #17063 | @gavindsouza
• build!: Declarative builds via pyproject.toml #17174 | @gavindsouza
• build!: Bump minimum Python version to 3.10 #17355 | @gavindsouza
• refactor: Site Migration #15877 | @gavindsouza
• refactor!: Don't cast values of frappe.db.get_singles_dict by default #17187 | @gavindsouza
• refactor!: make automatically following documents optional #16030 | @hasnain2808
• chore: Set esbuild target to es2017 #16491 | @netchampfaris
• fix!: remove unnecessary array transformation in request args #15784 | @netchampfaris
• refactor!: Remove Data Migration Tool #17134 | @netchampfaris
• refactor: remove parent, parenttype and parentfield columns from non-child table doctypes #15411 | @phot0n
• refactor!: remove post and post comment doctypes #15786 | @phot0n
• refactor(minor)!: remove is_first_startup from System Settings #16817 | @phot0n
• chore!: remove unused APIs from frappe.client #17446 | @resilient-tech
• fix!: dont delete custom permissions when doctype is deleted #17297 | @resilient-tech
• fix!: ignore DoesNotExistError inside get_cached_value #16454 | @resilient-tech
• fix!: remove unnecessary get_default API #17295 | @resilient-tech
• refactor!: improved frappe._dict #16449 | @resilient-tech
• refactor(BaseDocument)!: don't return __dict__ if key is falsy #16383 | @resilient-tech
• refactor(BaseDocument)!: improved get, set and extend methods #16540 | @resilient-tech
• feat(minor)!: Add document reference to Error Log and doc.log_error #16653 | @rmehta
• feat: Add a flag to identify system generated customization #16278 | @surajshetty3416
• refactor!: Replace incompatible libraries #17419 | @surajshetty3416
• refactor!: Database #16961 | @gavindsouza
• refactor!: GoogleOAuth #16935 | @phot0n
• refactor!: remove payment gateways (and related things) #16224 | @phot0n