Used by Google seemingly almost all around account sign in and
management. The modern sign in page has this near the beginning:
```html
<base href="https://accounts.google.com">
```
All of the XHRs performed by sign in are relative URLs to this
base URL. Previously we ignored this and did it relative to the
current URL, causing the XHRs to 404 and sign in to fall apart.
I presume they do this because you can access the sign in page
from multiple endpoints, such as `/ServiceLogin` and
`/o/oauth2/auth/identifier`
We had some inconsistencies before:
- Sometimes "The", sometimes "the"
- Sometimes trailing ".", sometimes no trailing "."
I picked the most common one (lowecase "the", trailing ".") and applied
it to all copyright headers.
By using the exact same string everywhere we can ensure nothing gets
missed during a global search (and replace), and that these
inconsistencies are not spread any further (as copyright headers are
commonly copied to new files).
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
