[psteinroe]

Stacked on #1103.

migrations.after was a u64, so it only worked for migration tools whose versions are plain numbers, and a value that matched no file name ignored nothing without saying so. Since #993, each migration tool reads the version of its migration files itself (MigrationTool::version), so after can be read the same way:

{ "migrations": { "migrationsDir": "migrations", "after": "0042" } }   // same as 42

What changed

• migrations.after is a MigrationVersion: a number or a string (#[serde(untagged)]), integer | string in schema.json. --after takes a VERSION; digits are read as a number. Existing configurations keep working.
• after and the version of each migration file are both read with the selected tool's version(), and a file is ignored when its version is at most after. All current tools read <number>_<name>.sql with leading zeros stripped, so "0042" and 42 are the same, as before.
• A value that isn't a version of the tool, like "v1", ignores nothing, as before, but now the CLI prints a warning and the editor shows one: "migrations.after is v1, which is not a version of goose migrations, so no migration is ignored. …". It's a new ConfigurationNotice::InvalidSettings, next to the deprecation notices. 0, the default, isn't reported.
• The tool of migrations.tool is looked up in one place now (settings::migration_tool).
• The migrations guide explains the format; just gen-lint regenerated schema.json, the TS bindings and the CLI reference.

Tests

• pgls_configuration: after_is_a_number_or_a_string (number, string, FromStr with leading zeros and text, negative numbers rejected).
• pgls_workspace: migrations_after_is_a_number_or_a_string (number and string, leading zeros in after and in file names, an invalid value ignoring nothing), reports_an_after_that_is_not_a_version_of_the_tool.
• nested_configurations_have_their_own_migrations_settings and the CLI --after tests are unchanged.

Not covered

• --after given on the command line isn't checked for the warning, only after in a configuration file.
• All tools still read numeric versions. Dotted (Flyway) or name-based (Sqitch) versions come with those tools.

Update: --after is checked too now. The configuration notices are about the file, so the CLI checks the configuration as applied when --after is given, with the tool of the file or of --migration-tool, and prints the same warning (after_argument_that_is_no_version_is_reported). The first "Not covered" item is done.