config: implement storage inheritance option

[niedbalski]

Adds storage inheritance logic allowing input instances to inherit global storage configuration.

Example configuration with global storage inheritance:

[SERVICE]
    storage.type filesystem
    storage.inherit on
    storage.path /tmp/fluent-bit-test
    flush 1
    daemon off

[INPUT]
    name dummy
    tag test.inherit
    # This input inherits filesystem storage from service

[INPUT] 
    name dummy
    tag test.override
    storage.type memory
    # This input overrides with explicit memory storage

[OUTPUT]
    name stdout
    match *

Expected behavior:

• First input uses filesystem storage (inherited from service)
• Second input uses memory storage (explicit override)
• Input instances without explicit storage.type inherit from global config when storage.inherit=on

Example configuration without global storage:

[SERVICE]
    storage.path /tmp/fluent-bit-test
    flush 1
    daemon off

[INPUT]
    name dummy
    tag test.default
    # Uses default memory storage (no inheritance)

[INPUT] 
    name dummy
    tag test.explicit
    storage.type filesystem
    # Uses explicit filesystem storage

[OUTPUT]
    name stdout
    match *

Expected behavior:

• First input defaults to memory storage
• Second input uses filesystem storage (explicit configuration)
• No inheritance occurs when storage.inherit is not enabled

[cosmo0920]

The logic seems good to me. But I found a nitpick. So, I still leave a comment now.

[cosmo0920]

From my side, it looks good.

[edsiper]

@niedbalski thank you. would you pls cleanup the commit history ?