Merge the devel branch into the main branch, v3.0.0

[akolotov]

The major version was increased since there is no backward compatibility anymore -- the endpoints sendTransaction and transactions were removed as part of #121.

This merge contains the following set of changes:

• Change RootSet approach to getRootAt (Change RootSet approach to getRootAt #119)
• Introduction of support id (Introduction of support id #121)
• New endpoint to get the relayer version (New endpoint to get the relayer version #122)
• Pause workers on insufficient balance error (Pause workers on insufficient balance error #123)
• Add HTTPS URL validation (Add HTTPS URL validation #124)
• RPC sync check introduction to switch to fallback RPCs (Add optional RPC sync check #128)
• Fix missing configuration variables (Fix missing configuration variables #130)
• Fix events block range (Fix events block range #134)