Add setSSLVersion and setBufferSizes to setHTTPOptions to limit memory usage

[se-fLa]

Proposal:
Add functions to set wifiClientSec->setSSLVersion() and wifiClientSec->setBufferSizes()

Would also like to be able to give a BearSSL::WiFiClientSecure so one can use multiple root certs

BearSSL::X509List trustedRoots_letsencrypt; // Holds our trusted root certs from Let's Encrypt
trustedRoots_letsencrypt.append(isrgrootx1);
trustedRoots_letsencrypt.append(isrg_root_x2);
xxx.setTrustAnchors(&trustedRoots_letsencrypt); // or set with HTTPOptions or in influxDbClient contructor as last argument

Current behavior:
Crashes with out of memory OOM on 8266 / ESP12 unless buffer set to 512,512

Desired behavior:
Possibility to configure bufferSizes for the BearSSL::WiFiClientSecure and also the SSL version.
I added as a test/quick fix in ESP8266_Influxdb/src/HTTPService.cpp::HTTPService constructor

   36: wifiClientSec->setSSLVersion(BR_TLS12, BR_TLS12);
   37: wifiClientSec->setBufferSizes(512, 512);

and that solved my crashes and also writePoint works (only validateConnection() work without this fix, not writePoint())

Alternatives considered:
Be able to provide own BearSSL::WiFiClientSecure object as HTTPOptions

Use case:
Crashes out of memory on ESP12.

[vlastahajek]

@se-fLa, nice suggestion, thanks.
MFLN procedure sets buffer sizes to 1024, when confirmed. So, when I allow overriding the MFN result, e.g. set small buffers, in your case, will 1024 buffer size also work?
Or, as you wrote, only 512B works for you?

[se-fLa]

Run into this bug again after reinstall of my machine and forgot about my patch.
512B works for me, then there is enough memory.
Would be great if this could be addressed.