The threee tags `<name>`, `</name>` and `<command>` were frequently used
with a leading space that this removes. The reason this habbit is so
widespread in testcases is probably that they have been copy and pasted.
Hence, fixing them all now might curb this practice from now on.
Closes#12028
Adding `bufq`:
- at init() time configured to hold up to `n` chunks of `m` bytes each.
- various methods for reading from and writing to it.
- `peek` support to get access to buffered data without copy
- `pass` support to allow buffer flushing on write if it becomes full
- use case: IO buffers for dynamic reads and writes that do not blow up
- distinct from `dynbuf` in that:
- it maintains a read position
- writes on a full bufq return CURLE_AGAIN instead of nuking itself
- Init options:
- SOFT_LIMIT: allow writes into a full bufq
- NO_SPARES: free empty chunks right away
- a `bufc_pool` that can keep a number of spare chunks to
be shared between different `bufq` instances
Adding `dynhds`:
- a straightforward list of name+value pairs as used for HTTP headers
- headers can be appended dynamically
- headers can be removed again
- headers can be replaced
- headers can be looked up
- http/1.1 formatting into a `dynbuf`
- configured at init() with limits on header counts and total string
sizes
- use case: pass a HTTP request or response around without being version
specific
- express a HTTP request without a curl easy handle (used in h2 proxy
tunnels)
- future extension possibilities:
- conversions of `dynhds` to nghttp2/nghttp3 name+value arrays
Closes#10720