Add `location` key (url, line, column) to `Get Page Errors` entries

Use case

Get Page Errors returns accumulated uncaught page errors, but pinpointing which script threw currently means parsing the free-form stack trace string — brittle and different per browser. Playwright 1.60 introduced the weberror context event, whose WebError carries a structured source location. Surfacing it lets users assert directly on the offending script URL, line and column, e.g. to verify a third-party script is (or is not) the source of console errors, without any string parsing. Today no structured alternative exists.

Proposed keyword / arguments

No new keyword and no signature change — each dict in the list returned by Get Page Errors gains a key:

• location — dict {url, line, column} of the error source (may be empty/None when the browser does not report a location)

*** Test Cases ***
Error Comes From Our Bundle Not The Ad Script
    New Page    ${TEST_APP_URL}/broken
    Click    id=trigger-error
    ${errors}=    Get Page Errors
    Should Contain    ${errors[0].location.url}    /static/app.bundle.js
    Should Be True    ${errors[0].location.line} > 0

The existing assertion-engine arguments of Get Page Errors keep working as before.

Playwright API

webError.location (v1.60), delivered via the browserContext.on('weberror') event.

Implementation notes

• node/playwright-wrapper/playwright-state.ts: the page-error accumulator currently feeds from the page-level pageerror event; switch (or augment) capture to the context-level weberror event so the location object is available, attributing each error to its page via webError.page(), and store location alongside the existing fields.
• Browser/keywords (get_page_errors): document the new location key. No proto changes expected — the entries already travel as JSON.
• atest: test-app page that throws from a known script/line; assert on location.url/line.

Backwards compatibility

Fully additive: the entry dicts only gain a location key; existing keys, ordering and the keyword signature are unchanged. Suites asserting on the message/stack text keep working.