fix: inputs/SALVIAS/validations.sql: plotMetadata.SiteCode: need to match types with the output query column

schemas/vegbien.sql: added public_validations.rm_all_queries(schema), which removes all validations queries in a schema, or in all schemas (useful when recreating validations queries from the DDL export file)

schemas/util.sql: validation_views(): moved filtering out of _validations schemas to validatable_datasources() so that calling this function with no args gives the validation views in *all schemas as one would expect

schemas/util.sql: query_relations(): support passing in an input query instead of an output query, which will remove only in the datasource's schema. (note that it was not clear that passing in an input-side query was not previously supported.)

schemas/util.sql: added schema_regexp(regclass)

schemas/vegbien.sql: schema_anchor: clarified that this identifies this function's schema (for use in locating helper functions), but is not necessarily the schema operated on, as the comment implied

schemas/util.sql: drop_relations_like(): use util.schema_regexp()

schemas/util.sql: added schema_regexp(schema_anchor)

fix: schemas/vegbien.sql: _plots_04_count_of_plots_in_each_project_in_this_source: count top-level plots to match the input query

schemas/vegbien.sql: remake_diff_table(): instructions for how to regenerate the diff table: put these at the beginning of the table comment instead of the end, because they are the most important info about the table that a user needs to know