[mono][aot] Prefer specific instances instead of gshared for methods …

[vargaz]

…containing static virtual calls.

These calls cannot be resolved at compile time in gshared methods, so they cannot be inlined etc. They are used in perf sensitive BCL code like SpanHelpers. To fix this, modify the AOT compiler so in addition to the gshared versions, it emits specific instances of these methods if possible. This only affects a small subset of gshared methods so it doesn't lead to a noticable code size increase.

Fixes #75801.

[vargaz]

/azp run runtime-wasm

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[vargaz]

Test failures are unrelated:
#76041

[vargaz]

/azp run runtime-wasm

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[lewing]

category=OuterLoop -notrait category=failing
[23:03:23] info: Application arguments: --run WasmTestRunner.dll System.Runtime.Tests.dll -notrait category=AdditionalTimezoneChecks -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing
[23:03:23] info: browser: [main] Console websocket connected.
[23:03:58] info: Initializing.....
[23:03:58] info: Discovering: System.Runtime.Tests.dll (method display = ClassAndMethod, method display options = None)
[23:04:02] info: Discovered:  System.Runtime.Tests.dll (found 8917 of 9067 test cases)
[23:04:02] info: Using random seed for test cases: 251347065
[23:04:02] info: Using random seed for collections: 251347065
[23:04:02] info: Starting:    System.Runtime.Tests.dll
[23:04:14] fail: 122030640
[23:04:14] fail: 122030640
[23:04:14] fail: 122030640
[23:04:14] fail: 122030640
[23:04:14] info: WASM EXIT 1
[23:04:14] info: Waiting to flush log messages with a timeout of 120 secs ..
[23:04:14] fail: [out of order message from the browser]: http://127.0.0.1:49207/test-main.js 342:0 Uncaught (in promise)
[23:04:14] fail: [out of order message from the browser]: http://127.0.0.1:49207/dotnet.js 1882:6 Uncaught
[23:04:14] fail: Application has finished with exit code TESTS_FAILED but 0 was expected
XHarness exit code: 71 (GENERAL_FAILURE)

C:\helix\work\workitem\e\wasm_build\AppBundle>set EXIT_CODE=71 

looks like #74302