* Update LwIP to 2.2.1
* Update to mbedtls to 3.6.1
* Update lib/cyw43-driver to 1.1.0
* Support using a more recent version of mbedtls
altcp_tls_mbedtls.c is not compatible with mbedtls 3.x so use a
patched version until this is resolved.
* Make sure MBEDTLS_VERSION_MAJOR is visible to LwIP.
* Test mbedtls in kitchen sink
* Add mbedtls to bazel
1. Make sure Pico SDK libraries have the correct dependencies on other SDK libraries
2. Pico SDK libraries all have _headers variants to include the headers. This may facilitate building user STATIC libraries without
pulling in SDK code, though care will still need to be taken w.r.t. values of #defines
3. Make sure the _headers versions also have the correct dependencies
Note: There are a few exceptions to 1. for some non code libraries like pico_standard_link and pico_cxx_options
* Add mbedtls as a submodule
Checked out on branch mbedtls-2.28
* Add mbedtls to pico-sdk
Link your code to pico_lwip_mbedtls and pico_mbedtls.
See tls_client example in pico-examples
Fixes https://github.com/raspberrypi/pico-sdk/issues/893
